Merge pull request #13989 from nextcloud/backport/13988/stable32

[stable32] feat: restrict calendar invitation participants

Author: SebastianKrupinski

admin_manual/groupware/calendar.rst

@@ -40,6 +40,12 @@ See :doc:`../configuration_server/email_configuration`.
 
 You must also make sure the "Send invitations to attendees" setting is activated in the admin setting groupware section for the emails to be sent.
 
+Administrators can disable the sending of invitations to external participants with the following command::
+
+ sudo -E -u www-data php occ config:app:set dav caldav_external_attendees_disabled --value yes
+
+This prevents invitations from being sent to attendees outside the instance and hides external contacts from the invitee search.
+
 Birthday calendar
 -----------------
 Contacts that have a birthday date filled are automatically added as events to a special Birthday calendar.