recovery: add create_admin_group management command

Signed-off-by: Jens Langhammer <jens.langhammer@beryju.org>

website/docs/troubleshooting/missing_admin_group.md

@@ -0,0 +1,17 @@
+---
+title: Missing admin group
+---
+
+If all of the Admin groups have been deleted, or misconfigured during sync, you can use the following command to gain access back.
+
+Run the following command, where *username* is the user you want to add to the newly created group:
+
+```
+docker-compose run --rm server create_admin_group username
+```
+
+or, for Kubernetes, run
+
+```
+kubectl exec -it deployment/authentik-worker -c authentik -- ak create_admin_group username
+```