minor #20851 [Messenger] Document stamps in HandleTrait::handle (Fan2Shrek)

This PR was squashed before being merged into the 7.3 branch.

Discussion
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[Messenger] Document stamps in HandleTrait::handle

Fix #20842

Commits
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97d301a [Messenger] Document stamps in HandleTrait::handle

Author: javiereguiluz

messenger.rst

@@ -2525,6 +2525,20 @@ wherever you need a query bus behavior instead of the ``MessageBusInterface``::
         }
     }
 
+You also can also add stamps when handling a message. For example, you can
+add an ``DoctrineFlushStamp`` to flush the entity manager after handling the message::
+
+    $this->handle(new SomeMessage($data), [new DoctrineFlushStamp()]);
+
+.. note::
+
+    If adding a stamp of the same type that already exists in the envelope,
+    both stamps will be kept (see `Envelopes & Stamps`_).
+
+.. versionadded:: 7.3
+
+    The ``$stamps`` parameter on the handle method was introduced in Symfony 7.3.
+
 Customizing Handlers
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