Merge pull request #115 from adrienbrault/handler-doc

Document the SubscribingHandlerInterface a bit

src/JMS/Serializer/Handler/SubscribingHandlerInterface.php

@@ -21,6 +21,19 @@ namespace JMS\Serializer\Handler;
 interface SubscribingHandlerInterface
 {
     /**
+     * Return format:
+     *
+     *      array(
+     *          array(
+     *              'direction' => GraphNavigator::DIRECTION_SERIALIZATION,
+     *              'format' => 'json',
+     *              'type' => 'DateTime',
+     *              'method' => 'serializeDateTimeToJson',
+     *          ),
+     *      )
+     *
+     * The direction and method keys can be omitted.
+     *
      * @return array
      */
     public static function getSubscribingMethods();