Merge branch '6.0' into 6.1

* 6.0:
  [Messenger] Add an info about redeliver_timeout (doctrine)

Author: javiereguiluz

messenger.rst

@@ -1293,6 +1293,12 @@ auto_setup          Whether the table should be created
                     automatically during send / get.       true
 ==================  =====================================  ======================
 
+.. note::
+
+    Set ``redeliver_timeout`` to a greater value than your slowest message
+    duration. Otherwise, some messages will start a second time while the
+    first one is still being handled.
+
 When using PostgreSQL, you have access to the following options to leverage
 the `LISTEN/NOTIFY`_ feature. This allow for a more performant approach
 than the default polling behavior of the Doctrine transport because