minor #4734 [BestPractices] add missing comma (xabbuh)

This PR was merged into the 2.3 branch.

Discussion
----------

[BestPractices] add missing comma

| Q             | A
| ------------- | ---
| Doc fix?      | yes
| New docs?     | no
| Applies to    | all
| Fixed tickets |

Commits
-------

46647c1 add missing comma and remove a serial comma

Author: wouterj

best_practices/security.rst

@@ -73,7 +73,7 @@ Authorization (i.e. Denying Access)
 -----------------------------------
 
 Symfony gives you several ways to enforce authorization, including the ``access_control``
-configuration in :doc:`security.yml </reference/configuration/security>` the
+configuration in :doc:`security.yml </reference/configuration/security>`, the
 :ref:`@Security annotation <best-practices-security-annotation>` and using
 :ref:`isGranted <best-practices-directly-isGranted>` on the ``security.context``
 service directly.
@@ -232,8 +232,8 @@ Now, you can use the voter with the ``@Security`` annotation:
         // ...
     }
 
-You can also use this directly with the ``security.context`` service, or
-via the even easier shortcut in a controller:
+You can also use this directly with the ``security.context`` service or via
+the even easier shortcut in a controller:
 
 .. code-block:: php