Use php-symfony code block type for method-level examples

The ``::`` shorthand creates PHP code blocks that fail syntax validation
because ``public function`` without a class context is invalid PHP.

Author: lacatoire

reference/events.rst

@@ -70,7 +70,9 @@ even to change the controller entirely::
     }
 
 You can also use ``getAttributes()`` to retrieve PHP attributes declared on the
-controller::
+controller:
+
+.. code-block:: php-symfony
 
     use Symfony\Component\HttpKernel\Event\ControllerEvent;
 
@@ -188,7 +190,9 @@ before sending it back (e.g. add/modify HTTP headers, add cookies, etc.)::
     }
 
 You can use ``getControllerAttributes()`` to retrieve PHP attributes declared
-on the controller that handled the request::
+on the controller that handled the request:
+
+.. code-block:: php-symfony
 
     use Symfony\Component\HttpKernel\Event\ResponseEvent;