docs(tutorials): updated Hello world

I made the Hello world tutorial clearer and included how to create the manifest file, which was missing completely but is required by newer (1.9+ apparently) versions of Elgg.

Fixes Elgg#9875

docs/tutorials/hello_world.rst

@@ -1,16 +1,45 @@
 Hello world
 ###########
 
-This tutorial shows you how to add a new page and print the text "Hello world" on it.
+This tutorial shows you how to create a new plugin that consists of a new page with the text "Hello world" on it.
+
+Before anything else, you need to :doc:`install Elgg</intro/install>`.
 
 In this tutorial we will pretend your site's URL is ``https://elgg.example.com``.
 
-First, you need to:
+First, create a directory that will contain the plugin's files. It should be located under the ``mod/`` directory which is located in your Elgg installation directory. So in this case, create ``mod/hello/``.
+
+Manifest file
+=============
+
+Elgg requires that your plugin has a manifest file that contains information about the plugin. Therefore, in the directory you just created, create a file called ``manifest.xml`` and copy this code into it:
+
+.. code-block:: xml
+
+    <?xml version="1.0" encoding="UTF-8"?>
+    <plugin_manifest xmlns="http://www.elgg.org/plugin_manifest/1.8">
+        <name>Hello world</name>
+        <id>hello</id>
+        <author>Your Name Here</author>
+        <version>0.1</version>
+        <description>Hello world, testing.</description>
+        <requires>
+            <type>elgg_release</type>
+            <version>2.0</version>
+        </requires>
+    </plugin_manifest>
 
- * :doc:`Install Elgg</intro/install>`
- * Create a file called ``start.php`` at the root of your app.
+This is the minimum amount of information in a manifest file:
 
-Copy this code into ``start.php``:
+- ``<name>`` is the display name of the plugin
+- ``<id>`` must be the same as the directory you just created
+- ``<requires>`` must include which version of Elgg your plugin requires
+- ``<author>``, ``<version>`` and ``<description>`` should have some appropriate values but can be filled freely
+
+Initializer
+===========
+
+Next, create ``start.php`` in the ``mod/hello/`` directory and copy this code into it:
 
 .. code-block:: php
 
@@ -22,7 +51,7 @@ Copy this code into ``start.php``:
     
     }
 
-This piece of code tells Elgg that it should call the function
+The above code tells Elgg that it should call the function
 ``hello_world_init()`` once the Elgg core system is initiated.
 
 Registering a page handler
@@ -31,7 +60,7 @@ Registering a page handler
 The next step is to register a page handler which has the purpose of handling
 request that users make to the URL ``https://elgg.example.com/hello``.
 
-Update the ``start.php`` to look like this:
+Update ``start.php`` to look like this:
 
 .. code-block:: php
 
@@ -48,13 +77,15 @@ Update the ``start.php`` to look like this:
     }
 
 The call to ``elgg_register_page_handler()`` tells Elgg that it should
-call the function ``hello_world_page_handler()`` when user goes navigates to 
+call the function ``hello_world_page_handler()`` when a user navigates to 
 ``https://elgg.example.com/hello/*``.
 
-The ``hello_world_page_handler()`` passes off rendering the actual page to the
-``resources/hello`` view. 
+The ``hello_world_page_handler()`` passes off rendering the actual page to a view file called ``hello.php``.
+
+View file
+=========
 
-Create ``views/default/resources/hello.php`` with this content:
+Create ``mod/hello/views/default/resources/hello.php`` with this content:
 
 .. code-block:: php
 
@@ -71,7 +102,7 @@ Create ``views/default/resources/hello.php`` with this content:
     echo elgg_view_page('Hello', $body);
 
 
-We give an array of parameters to the ``elgg_view_layout()`` function, including:
+The code creates an array of parameters to be given to the ``elgg_view_layout()`` function, including:
 
  - The title of the page
  - The contents of the page
@@ -80,4 +111,9 @@ We give an array of parameters to the ``elgg_view_layout()`` function, including
 This creates the basic layout for the page. The layout is then run through
 ``elgg_view_page()`` which assembles and outputs the full page.
 
-You can now go to the address https://elgg.example.com/hello/ and you should see your new page!
+Last step
+=========
+
+Finally, activate the plugin through your Elgg administrator page: ``https://elgg.example.com/admin/plugins`` (the new plugin appears at the bottom).
+
+You can now go to the address ``https://elgg.example.com/hello/`` and you should see your new page!