Refactor documentation assuming we use Symfony Flex

Author: elescot

best_practices/controllers.rst

@@ -47,8 +47,13 @@ this suffix is neither required nor recommended, so you can safely remove it.
 Routing Configuration
 ---------------------
 
-To load routes defined as annotations in your controllers and if you are not using Symfony Flex, add the following
-configuration to the annotation routing configuration file:
+To load routes defined as annotations in your controllers, run the following command :
+
+.. code-block:: terminal
+
+    $ composer require doctrine/annotations
+
+Thanks to the :doc:`Flex recipe</setup/flex>`, a ``config/routes/annotations.yaml`` file will be created:
 
 .. code-block:: yaml