Update 2.52.md

Author: valentijnscholten

docs/content/en/open_source/upgrading/2.52.md

@@ -21,9 +21,10 @@ If you want to be 110% sure no tasks will be lost you could perform the upgrade
 
 `docker compose down nginx, uwsgi, celerybeat`
 
-2) Observe the logs of the celeryworker(s) and wait until all tasks are finished:
+2) Observe the Redis queue and/or the logs of the celeryworker(s) and wait until all tasks are finished:
 
-`docker compose logs celeryworker`
+`docker compose exec redis redis-cli llen celery` -- should output 0
+`docker compose logs celeryworker` -- should stop outputting new task logs
 
 3) Stop the remaining services: