Earlier we use to restrict admins, moderators or members of a group to
manage that group if they were part of the realm wide
`can_manage_all_groups`. We will not do that anymore and even
non-members of a group regardless of role can manage a group if they are
part of `can_manage_all_groups`.
See
https://chat.zulip.org/#narrow/stream/101-design/topic/Group.20add.20members.20dropdown/near/1952902
to check more about the migration plan for which this is the last step.
In the help center and production documentation, replace links to
the "Getting your organization started with Zulip" guide to the
new "Moving to Zulip" guide.