fixing method name: addSubscriberMethod should be addSubscriber + added path to API doc

Author: saadtazi

book/internals/event_dispatcher.rst

@@ -409,7 +409,7 @@ and ``onStoreOrder`` events:
 
 This is very similar to a listener class, except that the class itself can
 tell the dispatcher which events it should listen to. To register a subscriber
-with the dispatcher, use the ``addSubscriberMethod`` method:
+with the dispatcher, use the :method:``Symfony\Component\EventDispatcher\EventDispatcher::addSubscriber`` method:
 
 .. code-block:: php