correct markdown usage [ci skip]

CONTRIBUTING.md

@@ -12,5 +12,5 @@ Ruby on Rails is a volunteer effort. We encourage you to pitch in. [Join the tea
 
 * If you have a change or new feature in mind, please [suggest it on the rubyonrails-core mailing list](https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core) and start writing code.
 
-Thanks! :heart: :heart: :heart: <br />
+Thanks! :heart: :heart: :heart:  
 Rails Team

guides/source/active_record_callbacks.md

@@ -15,7 +15,7 @@ After reading this guide, you will know:
 The Object Life Cycle
 ---------------------
 
-During the normal operation of a Rails application, objects may be created, updated, and destroyed. Active Record provides hooks into this <em>object life cycle</em> so that you can control your application and its data.
+During the normal operation of a Rails application, objects may be created, updated, and destroyed. Active Record provides hooks into this *object life cycle* so that you can control your application and its data.
 
 Callbacks allow you to trigger logic before or after an alteration of an object's state.
 

guides/source/active_support_core_extensions.md

@@ -1165,9 +1165,9 @@ Inserting data into HTML templates needs extra care. For example, you can't just
 
 #### Safe Strings
 
-Active Support has the concept of <i>(html) safe</i> strings. A safe string is one that is marked as being insertable into HTML as is. It is trusted, no matter whether it has been escaped or not.
+Active Support has the concept of _(html) safe_ strings. A safe string is one that is marked as being insertable into HTML as is. It is trusted, no matter whether it has been escaped or not.
 
-Strings are considered to be <i>unsafe</i> by default:
+Strings are considered to be _unsafe_ by default:
 
 ```ruby
 "".html_safe? # => false

guides/source/api_documentation_guidelines.md

@@ -79,7 +79,7 @@ used. Instead of:
 English
 -------
 
-Please use American English (<em>color</em>, <em>center</em>, <em>modularize</em>, etc). See [a list of American and British English spelling differences here](http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences).
+Please use American English (*color*, *center*, *modularize*, etc). See [a list of American and British English spelling differences here](http://en.wikipedia.org/wiki/American_and_British_English_spelling_differences).
 
 Example Code
 ------------

guides/source/asset_pipeline.md

@@ -124,19 +124,19 @@ with a built-in helper. In the source the generated code looked like this:
 The query string strategy has several disadvantages:
 
 1. **Not all caches will reliably cache content where the filename only differs by
-query parameters**<br>
+query parameters**  
     [Steve Souders recommends](http://www.stevesouders.com/blog/2008/08/23/revving-filenames-dont-use-querystring/),
  "...avoiding a querystring for cacheable resources". He found that in this
 case 5-20% of requests will not be cached. Query strings in particular do not
 work at all with some CDNs for cache invalidation.
 
-2. **The file name can change between nodes in multi-server environments.**<br>
+2. **The file name can change between nodes in multi-server environments.**  
     The default query string in Rails 2.x is based on the modification time of
 the files. When assets are deployed to a cluster, there is no guarantee that the
 timestamps will be the same, resulting in different values being used depending
 on which server handles the request.
 
-3. **Too much cache invalidation**<br>
+3. **Too much cache invalidation**  
     When static assets are deployed with each new release of code, the mtime
 (time of last modification) of _all_ these files changes, forcing all remote
 clients to fetch them again, even when the content of those assets has not changed.

guides/source/association_basics.md

@@ -1131,7 +1131,7 @@ The `has_one` association supports these options:
 
 ##### `:as`
 
-Setting the `:as` option indicates that this is a polymorphic association. Polymorphic associations were discussed in detail <a href="#polymorphic-associations">earlier in this guide</a>.
+Setting the `:as` option indicates that this is a polymorphic association. Polymorphic associations were discussed in detail [earlier in this guide](#polymorphic-associations).
 
 ##### `:autosave`
 
@@ -1203,7 +1203,7 @@ The `:source_type` option specifies the source association type for a `has_one :
 
 ##### `:through`
 
-The `:through` option specifies a join model through which to perform the query. `has_one :through` associations were discussed in detail <a href="#the-has-one-through-association">earlier in this guide</a>.
+The `:through` option specifies a join model through which to perform the query. `has_one :through` associations were discussed in detail [earlier in this guide](#the-has-one-through-association).
 
 ##### `:validate`
 
@@ -1497,7 +1497,7 @@ The `has_many` association supports these options:
 
 ##### `:as`
 
-Setting the `:as` option indicates that this is a polymorphic association, as discussed <a href="#polymorphic-associations">earlier in this guide</a>.
+Setting the `:as` option indicates that this is a polymorphic association, as discussed [earlier in this guide](#polymorphic-associations).
 
 ##### `:autosave`
 
@@ -1579,7 +1579,7 @@ The `:source_type` option specifies the source association type for a `has_many
 
 ##### `:through`
 
-The `:through` option specifies a join model through which to perform the query. `has_many :through` associations provide a way to implement many-to-many relationships, as discussed <a href="#the-has-many-through-association">earlier in this guide</a>.
+The `:through` option specifies a join model through which to perform the query. `has_many :through` associations provide a way to implement many-to-many relationships, as discussed [earlier in this guide](#the-has-many-through-association).
 
 ##### `:validate`
 
@@ -1632,7 +1632,7 @@ If you use a hash-style `where` option, then record creation via this associatio
 
 ##### `extending`
 
-The `extending` method specifies a named module to extend the association proxy. Association extensions are discussed in detail <a href="#association-extensions">later in this guide</a>.
+The `extending` method specifies a named module to extend the association proxy. Association extensions are discussed in detail [later in this guide](#association-extensions).
 
 ##### `group`
 
@@ -2082,7 +2082,7 @@ If you use a hash-style `where`, then record creation via this association will
 
 ##### `extending`
 
-The `extending` method specifies a named module to extend the association proxy. Association extensions are discussed in detail <a href="#association-extensions">later in this guide</a>.
+The `extending` method specifies a named module to extend the association proxy. Association extensions are discussed in detail [later in this guide](#association-extensions).
 
 ##### `group`
 

guides/source/caching_with_rails.md

@@ -185,7 +185,7 @@ end
 Cache Stores
 ------------
 
-Rails provides different stores for the cached data created by <b>action</b> and <b>fragment</b> caches.
+Rails provides different stores for the cached data created by **action** and **fragment** caches.
 
 TIP: Page caches are always stored on disk.
 

guides/source/contributing_to_ruby_on_rails.md

@@ -109,9 +109,7 @@ After applying their branch, test it out! Here are some things to think about:
 
 Once you're happy that the pull request contains a good change, comment on the GitHub issue indicating your approval. Your comment should indicate that you like the change and what you like about it. Something like:
 
-<blockquote>
-I like the way you've restructured that code in generate_finder_sql - much nicer. The tests look good too.
-</blockquote>
+>I like the way you've restructured that code in generate_finder_sql - much nicer. The tests look good too.
 
 If your comment simply says "+1", then odds are that other reviewers aren't going to take it too seriously. Show that you took the time to review the pull request.
 

guides/source/getting_started.md

@@ -450,9 +450,7 @@ available, Rails errors out.
 In the above image, the bottom line has been truncated. Let's see what the full
 thing looks like:
 
-<blockquote>
-Missing template articles/new, application/new with {locale:[:en], formats:[:html], handlers:[:erb, :builder, :coffee]}. Searched in: * "/path/to/blog/app/views"
-</blockquote>
+>Missing template articles/new, application/new with {locale:[:en], formats:[:html], handlers:[:erb, :builder, :coffee]}. Searched in: * "/path/to/blog/app/views"
 
 That's quite a lot of text! Let's quickly go through and understand what each
 part of it does.
@@ -498,8 +496,8 @@ harmoniously! It's time to create the form for a new article.
 
 ### The first form
 
-To create a form within this template, you will use a <em>form
-builder</em>. The primary form builder for Rails is provided by a helper
+To create a form within this template, you will use a *form
+builder*. The primary form builder for Rails is provided by a helper
 method called `form_for`. To use this method, add this code into
 `app/views/articles/new.html.erb`:
 

guides/source/i18n.md

@@ -107,7 +107,7 @@ The **translations load path** (`I18n.load_path`) is just a Ruby Array of paths
 
 NOTE: The backend will lazy-load these translations when a translation is looked up for the first time. This makes it possible to just swap the backend with something else even after translations have already been announced.
 
-The default `application.rb` files has instructions on how to add locales from another directory and how to set a different default locale. Just uncomment and edit the specific lines.
+The default `application.rb` file has instructions on how to add locales from another directory and how to set a different default locale. Just uncomment and edit the specific lines.
 
 ```ruby
 # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
@@ -137,7 +137,7 @@ If you want to translate your Rails application to a **single language other tha
 
 However, you would probably like to **provide support for more locales** in your application. In such case, you need to set and pass the locale between requests.
 
-WARNING: You may be tempted to store the chosen locale in a _session_ or a <em>cookie</em>. However, **do not do this**. The locale should be transparent and a part of the URL. This way you won't break people's basic assumptions about the web itself: if you send a URL to a friend, they should see the same page and content as you. A fancy word for this would be that you're being [<em>RESTful</em>](http://en.wikipedia.org/wiki/Representational_State_Transfer). Read more about the RESTful approach in [Stefan Tilkov's articles](http://www.infoq.com/articles/rest-introduction). Sometimes there are exceptions to this rule and those are discussed below.
+WARNING: You may be tempted to store the chosen locale in a _session_ or a *cookie*. However, **do not do this**. The locale should be transparent and a part of the URL. This way you won't break people's basic assumptions about the web itself: if you send a URL to a friend, they should see the same page and content as you. A fancy word for this would be that you're being [*RESTful*](http://en.wikipedia.org/wiki/Representational_State_Transfer). Read more about the RESTful approach in [Stefan Tilkov's articles](http://www.infoq.com/articles/rest-introduction). Sometimes there are exceptions to this rule and those are discussed below.
 
 The _setting part_ is easy. You can set the locale in a `before_action` in the `ApplicationController` like this:
 
@@ -262,7 +262,7 @@ get '/:locale' => 'dashboard#index'
 
 Do take special care about the **order of your routes**, so this route declaration does not "eat" other ones. (You may want to add it directly before the `root :to` declaration.)
 
-NOTE: Have a look at two plugins which simplify work with routes in this way: Sven Fuchs's [routing_filter](https://github.com/svenfuchs/routing-filter/tree/master) and Raul Murciano's [translate_routes](https://github.com/raul/translate_routes/tree/master).
+NOTE: Have a look at two plugins which simplify working with routes in this way: Sven Fuchs's [routing_filter](https://github.com/svenfuchs/routing-filter/tree/master) and Raul Murciano's [translate_routes](https://github.com/raul/translate_routes/tree/master).
 
 ### Setting the Locale from the Client Supplied Information
 

guides/source/security.md

@@ -25,7 +25,7 @@ The Gartner Group however estimates that 75% of attacks are at the web applicati
 
 The threats against web applications include user account hijacking, bypass of access control, reading or modifying sensitive data, or presenting fraudulent content. Or an attacker might be able to install a Trojan horse program or unsolicited e-mail sending software, aim at financial enrichment or cause brand name damage by modifying company resources. In order to prevent attacks, minimize their impact and remove points of attack, first of all, you have to fully understand the attack methods in order to find the correct countermeasures. That is what this guide aims at.
 
-In order to develop secure web applications you have to keep up to date on all layers and know your enemies. To keep up to date subscribe to security mailing lists, read security blogs and make updating and security checks a habit (check the <a href="#additional-resources">Additional Resources</a> chapter). It is done manually because that's how you find the nasty logical security problems.
+In order to develop secure web applications you have to keep up to date on all layers and know your enemies. To keep up to date subscribe to security mailing lists, read security blogs and make updating and security checks a habit (check the [Additional Resources](#additional-resources) chapter). It is done manually because that's how you find the nasty logical security problems.
 
 Sessions
 --------
@@ -68,7 +68,7 @@ Hence, the cookie serves as temporary authentication for the web application. An
 
 * Most people don't clear out the cookies after working at a public terminal. So if the last user didn't log out of a web application, you would be able to use it as this user. Provide the user with a _log-out button_ in the web application, and _make it prominent_.
 
-* Many cross-site scripting (XSS) exploits aim at obtaining the user's cookie. You'll read <a href="#cross-site-scripting-xss">more about XSS</a> later.
+* Many cross-site scripting (XSS) exploits aim at obtaining the user's cookie. You'll read [more about XSS](#cross-site-scripting-xss) later.
 
 * Instead of stealing a cookie unknown to the attacker, they fix a user's session identifier (in the cookie) known to them. Read more about this so-called session fixation later.
 
@@ -187,7 +187,7 @@ This attack method works by including malicious code or a link in a page that ac
 
 ![](images/csrf.png)
 
-In the <a href="#sessions">session chapter</a> you have learned that most Rails applications use cookie-based sessions. Either they store the session id in the cookie and have a server-side session hash, or the entire session hash is on the client-side. In either case the browser will automatically send along the cookie on every request to a domain, if it can find a cookie for that domain. The controversial point is, that it will also send the cookie, if the request comes from a site of a different domain. Let's start with an example:
+In the [session chapter](#sessions) you have learned that most Rails applications use cookie-based sessions. Either they store the session id in the cookie and have a server-side session hash, or the entire session hash is on the client-side. In either case the browser will automatically send along the cookie on every request to a domain, if it can find a cookie for that domain. The controversial point is, that it will also send the cookie, if the request comes from a site of a different domain. Let's start with an example:
 
 * Bob browses a message board and views a post from a hacker where there is a crafted HTML image element. The element references a command in Bob's project management application, rather than an image file.
 * `<img src="http://www.webapp.com/project/1/destroy">`
@@ -257,7 +257,7 @@ end
 
 The above method can be placed in the `ApplicationController` and will be called when a CSRF token is not present or is incorrect on a non-GET request.
 
-Note that _cross-site scripting (XSS) vulnerabilities bypass all CSRF protections_. XSS gives the attacker access to all elements on a page, so they can read the CSRF security token from a form or directly submit the form. Read <a href="#cross-site-scripting-xss">more about XSS</a> later.
+Note that _cross-site scripting (XSS) vulnerabilities bypass all CSRF protections_. XSS gives the attacker access to all elements on a page, so they can read the CSRF security token from a form or directly submit the form. Read [more about XSS](#cross-site-scripting-xss) later.
 
 Redirection and Files
 ---------------------
@@ -477,7 +477,7 @@ config.filter_parameters << :password
 
 INFO: _Do you find it hard to remember all your passwords? Don't write them down, but use the initial letters of each word in an easy to remember sentence._
 
-Bruce Schneier, a security technologist, [has analyzed](http://www.schneier.com/blog/archives/2006/12/realworld_passw.html) 34,000 real-world user names and passwords from the MySpace phishing attack mentioned <a href="#examples-from-the-underground">below</a>. It turns out that most of the passwords are quite easy to crack. The 20 most common passwords are:
+Bruce Schneier, a security technologist, [has analyzed](http://www.schneier.com/blog/archives/2006/12/realworld_passw.html) 34,000 real-world user names and passwords from the MySpace phishing attack mentioned [below](#examples-from-the-underground). It turns out that most of the passwords are quite easy to crack. The 20 most common passwords are:
 
 password1, abc123, myspace1, password, blink182, qwerty1, ****you, 123abc, baseball1, football1, 123456, soccer, monkey1, liverpool1, princess1, jordan23, slipknot1, superman1, iloveyou1, and monkey.
 
@@ -630,7 +630,7 @@ Also, the second query renames some columns with the AS statement so that the we
 
 #### Countermeasures
 
-Ruby on Rails has a built-in filter for special SQL characters, which will escape ' , " , NULL character and line breaks. <em class="highlight">Using `Model.find(id)` or `Model.find_by_some thing(something)` automatically applies this countermeasure</em>. But in SQL fragments, especially <em class="highlight">in conditions fragments (`where("...")`), the `connection.execute()` or `Model.find_by_sql()` methods, it has to be applied manually</em>.
+Ruby on Rails has a built-in filter for special SQL characters, which will escape ' , " , NULL character and line breaks. *Using `Model.find(id)` or `Model.find_by_some thing(something)` automatically applies this countermeasure*. But in SQL fragments, especially *in conditions fragments (`where("...")`), the `connection.execute()` or `Model.find_by_sql()` methods, it has to be applied manually*.
 
 Instead of passing a string to the conditions option, you can pass an array to sanitize tainted strings like this:
 

guides/source/testing.md

@@ -144,7 +144,7 @@ In Rails, models tests are what you write to test your models.
 
 For this guide we will be using Rails _scaffolding_. It will create the model, a migration, controller and views for the new resource in a single operation. It will also create a full test suite following Rails best practices. We will be using examples from this generated code and will be supplementing it with additional examples where necessary.
 
-NOTE: For more information on Rails <i>scaffolding</i>, refer to [Getting Started with Rails](getting_started.html)
+NOTE: For more information on Rails _scaffolding_, refer to [Getting Started with Rails](getting_started.html)
 
 When you use `rails generate scaffold`, for a resource among other things it creates a test stub in the `test/models` folder: