help: Add delete a user group instruction.
help: Add delete a user group instruction.

Fixes #22591.

zulip/zulip,zulip/zulip,rht/zulip,andersk/zulip,zulip/zulip,rht/zulip,andersk/zulip,andersk/zulip,zulip/zulip,andersk/zulip,zulip/zulip,andersk/zulip,rht/zulip,andersk/zulip,rht/zulip,rht/zulip,zulip/zulip,rht/zulip,rht/zulip,zulip/zulip,andersk/zulip