minor #20117 Add the missing note on how to inject a service into the controller (wkania)

This PR was merged into the 5.4 branch.

Discussion
----------

Add the missing note on how to inject a service into the controller

Without it there is an error:

Could not resolve argument of "Controller", maybe you forgot to register the controller as a service or missed tagging it with the "controller.service_arguments"?

Commits
-------

be7999e Add the missing note on how to inject a service into the controller

Author: javiereguiluz

controller.rst

@@ -178,7 +178,8 @@ These are used for rendering templates, sending emails, querying the database an
 any other "work" you can think of.
 
 If you need a service in a controller, type-hint an argument with its class
-(or interface) name. Symfony will automatically pass you the service you need::
+(or interface) name. Symfony will automatically pass you the service you need.
+Make sure your :doc:`controller is registered as a service </controller/service>`::
 
     use Psr\Log\LoggerInterface;
     use Symfony\Component\HttpFoundation\Response;