minor #14437 [Messenger] Update messenger.rst (ahmed-bhs)

This PR was submitted for the 5.x branch but it was merged into the 4.4 branch instead.

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[Messenger] Update messenger.rst

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7b441a2 Update messenger.rst

Author: javiereguiluz

messenger.rst

@@ -472,7 +472,7 @@ On production, there are a few important things to think about:
     process control system like :ref:`Supervisor <messenger-supervisor>`.
 
 **Don't Let Workers Run Forever**
-    Some services (like Doctrine's EntityManager) will consume more memory
+    Some services (like Doctrine's ``EntityManager``) will consume more memory
     over time. So, instead of allowing your worker to run forever, use a flag
     like ``messenger:consume --limit=10`` to tell your worker to only handle 10
     messages before exiting (then Supervisor will create a new process). There