Add documentation about CELERY_TASK_RESULT_EXPIRES
@@ -1082,6 +1082,8 @@ stored task tombstones will be deleted.
A built-in periodic task will delete the results after this time
(:class:`celery.task.backend_cleanup`).
+Setting it to None or 0 will disable results cleanup.
+
Default is to expire after 1 day.
.. note::
Ask Solem Hoel