minor #16521 [Notifier] Update route from annotation to attribute (94noni)

This PR was merged into the 5.4 branch.

Discussion
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[Notifier] Update route from annotation to attribute

I was reading some doc around this notifier component and found this is worth it

Commits
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eaa7f02 Update route from annotation to attribute

Author: javiereguiluz

notifier.rst

@@ -479,9 +479,7 @@ To send a notification, autowire the
 
     class InvoiceController extends AbstractController
     {
-        /**
-         * @Route("/invoice/create")
-         */
+        #[Route('/invoice/create')]
         public function create(NotifierInterface $notifier)
         {
             // ...
@@ -613,9 +611,7 @@ sent using the Slack transport::
     // ...
     class InvoiceController extends AbstractController
     {
-        /**
-         * @Route("/invoice/create")
-         */
+        #[Route('/invoice/create')]
         public function invoice(NotifierInterface $notifier)
         {
             // ...