[Messenger] Document the changes in the delete_after_ack Redis option

Author: javiereguiluz

messenger.rst

@@ -1354,7 +1354,7 @@ The Redis transport DSN may looks like this:
     # .env
     MESSENGER_TRANSPORT_DSN=redis://localhost:6379/messages
     # Full DSN Example
-    MESSENGER_TRANSPORT_DSN=redis://password@localhost:6379/messages/symfony/consumer?auto_setup=true&serializer=1&stream_max_entries=0&dbindex=0
+    MESSENGER_TRANSPORT_DSN=redis://password@localhost:6379/messages/symfony/consumer?auto_setup=true&serializer=1&stream_max_entries=0&dbindex=0&delete_after_ack=true
     # Redis Cluster Example
     MESSENGER_TRANSPORT_DSN=redis://host-01:6379,redis://host-02:6379,redis://host-03:6379,redis://host-04:6379
     # Unix Socket Example
@@ -1427,6 +1427,12 @@ claim_interval       Interval on which pending/abandoned    ``60000`` (1 Minute)
 
     The ``delete_after_reject`` and ``lazy`` options were introduced in Symfony 5.2.
 
+.. deprecated:: 5.4
+
+    Not setting a explicit value for the ``delete_after_ack`` option is
+    deprcated since Symfony 5.4. In Symfony 6.0, the default value of this
+    option changes from ``false`` to ``true``.
+
 In Memory Transport
 ~~~~~~~~~~~~~~~~~~~