Merge pull request #2810 from sww/remove-extra-on-retry

Removed an extra on_retry entry in the docs.

docs/userguide/tasks.rst

@@ -1259,9 +1259,6 @@ Handlers
 
     The return value of this handler is ignored.
 
-on_retry
-~~~~~~~~
-
 .. _task-how-they-work:
 
 How it works