Tweak documentation to make mdl 0.5.0 happy

mdl version 0.5.0 complains about a few markdown constructs...
it's no big deal to change them, so let's change them.

Note that this does NOT switch to mdl 0.5.0.  There's some
odd problem in installing it, so I'm waiting for another time
to do that.

Signed-off-by: David A. Wheeler <dwheeler@dwheeler.com>

CONTRIBUTING.md

@@ -114,14 +114,18 @@ Another way to do this is to write the following at the end of the commit
 message, on a line by itself separated by a blank line from the body of
 the commit:
 
-    Signed-off-by: YOUR NAME <YOUR.EMAIL@EXAMPLE.COM>
+````
+Signed-off-by: YOUR NAME <YOUR.EMAIL@EXAMPLE.COM>
+````
 
 You can signoff by default in this project by creating a file
 (say "git-template") that contains
 some blank lines and the signed-off-by text above;
 then configure git to use that as a commit template.  For example:
 
-    git config commit.template ~/cii-best-practices-badge/git-template
+````sh
+git config commit.template ~/cii-best-practices-badge/git-template
+````
 
 It's not practical to fix old contributions in git, so if one is forgotten,
 do not try to fix them.  We presume that if someone sometimes used a DCO,

doc/INSTALL.md

@@ -347,10 +347,7 @@ the install script.
 In order to completely remove the Badge app, perform the following steps:
 
 1.  Remove the database entries Badge app.  This can be done by running
-
-    ~~~~
-    rake db:drop && RAILS_ENV=test rake db:drop
-    ~~~~
+    "rake db:drop && RAILS_ENV=test rake db:drop"
 
 2.  Remove the cii-best-practices-badge directory. (WARNING: This will remove
     any and all local branches that have not been pushed to your remote git
@@ -359,12 +356,14 @@ In order to completely remove the Badge app, perform the following steps:
 3.  (Optional) If you do not use rbenv for any other applications and would
     like to remove it, you can co so by first removing the directory:
     `$HOME/.rbenv`.   Finally remove the any lines matching "rbenv" from any
-    shell startup files.  You can find these entries with the following
-    command
+    shell startup files.
+
+You can find lines matching "rbenv" in shell startup files
+with the following shell command:
 
-    ~~~~sh
-    grep rbenv ~/.bashrc ~/.bash_profile ~/.zshrc /etc/profile /etc/profile.d/*
-    ~~~~
+~~~~sh
+grep rbenv ~/.bashrc ~/.bash_profile ~/.zshrc /etc/profile /etc/profile.d/*
+~~~~
 
 ## See also
 

doc/api.md

@@ -15,7 +15,9 @@ For example, you can get the JSON data for project #1 from the
 real production site (<https://bestpractices.coreinfrastructure.org>)
 by retrieving (a GET) data from this URL:
 
-    https://bestpractices.coreinfrastructure.org/projects/1.json
+````
+https://bestpractices.coreinfrastructure.org/projects/1.json
+````
 
 Note that you can ask for a particular result data format (where
 supported) by adding a period and its format (e.g., ".json", ".csv",
@@ -34,7 +36,9 @@ we'll indicate variables by beginning their name with ":" (colon).
 So the URL above is an example of this pattern, which retrieves
 information about project :id in a given :format (HTML by default):
 
-    GET /projects/:id(.:format)
+````
+GET /projects/:id(.:format)
+````
 
 ## Most common requests
 
@@ -72,7 +76,9 @@ might request.
 The "/projects" URL supports various searches.
 For example, retrieving this URL:
 
-    /projects.json?gteq=90&amp;lteq=99&amp;page=2
+````
+/projects.json?gteq=90&amp;lteq=99&amp;page=2
+````
 
 Will retrieve a list of project data in JSON format, but only for
 projects with 90% or better passing *and* less than or equal to 99%