Update security.rst

Co-authored-by: Oskar Stark <[email protected]>

Author: johnkrovitch

security.rst

@@ -696,8 +696,6 @@ be authenticated against. For built-in authenticators, you can pass an authentic
 ``http_basic``... For custom authenticators, you can pass the service id of the authenticator
 (i.e. `App\\Security\\Authenticator\\ExampleAuthenticator`)::
 
-.. code-block:: php
-
 use App\Security\Authenticator\ExampleAuthenticator;
 use Symfony\Bundle\SecurityBundle\Security\Security;