feature #12231 Explain how to add from_transport on messenger.message_handler tag (ruudk)

This PR was squashed before being merged into the 4.4 branch (closes #12231).

Discussion
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Explain how to add `from_transport` on `messenger.message_handler` tag

See symfony/symfony#33317

Commits
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03ed48e Explain how to add `from_transport` on `messenger.message_handler` tag

Author: wouterj

messenger.rst

@@ -1229,6 +1229,15 @@ Then, make sure to "route" your message to *both* transports:
 
 That's it! You can now consume each transport:
 
+.. note::
+
+    It is possible to specify ``from_transport`` as attribute on the ``messenger.message_handler`` tag.
+
+    .. versionadded:: 4.4
+        
+        The ability to specify ``from_transport`` on the ``messenger.message_handler`` tag
+        itself, was added in Symfony 4.4.
+
 .. code-block:: terminal
 
     # will only call ThumbnailUploadedImageHandler when handling the message