More comprehensive documentation of event handlers

doc/articles/plugins.md

@@ -89,9 +89,45 @@ Furthermore plugins may implement the
 event handlers automatically registered with the `EventDispatcher` when the
 plugin is loaded.
 
-Plugin can subscribe to any of the available [script events](scripts.md#event-names).
+To register a method to an event, implement the method `getSubscribedEvents()` and have it return an array. The array key must be the event name ([listed here](https://getcomposer.org/doc/articles/scripts.md#event-names)) and the value is the name of the method in this class to be called.
 
-Example:
+```php
+public static function getSubscribedEvents()
+{
+    return array(
+        'post-autoload-dump' => 'methodToBeCalled',
+        // ^ event name ^         ^ method name ^                   
+    );
+}
+```
+
+By default, the priority of an event handler is set to 0. The priorty can be changed by attaching a tuple where the first value is the method name, as before, and the second value is an integer representing the priority. Higher integers represent higher priorityes therefore, priortity 2 is called before priority 1, etc.
+
+```php
+public static function getSubscribedEvents()
+{
+    return array(
+        // Will be called before events with priority 0
+        'post-autoload-dump' => array('methodToBeCalled', 1) 
+    );
+}
+```
+
+If multiple methods should be called, then an array of tupples can be attached to each event. The tupples do not need to include the priority. If it is omitted, it will default to 0.
+
+```php
+public static function getSubscribedEvents()
+{
+    return [
+        'post-autoload-dump' => array(
+            array('methodToBeCalled'      ), // Priority defaults to 0
+            array('someOtherMethodName', 1), // This fires first
+        )
+    ];
+}
+```
+
+Here's a complete example:
 
 ```php
 <?php