tips: Clarify department sandboxing

include/i18n/en_US/help/tips/staff.department.yaml

@@ -73,9 +73,9 @@ sandboxing:
     title: Ticket Assignment Restrictions
     content: >
         Enable this to restrict ticket assignement to only include members
-        of this Department. Department access can be extended to
-        Groups, if <span class="doc-desc-title">Group Membership</span> is
-        also enabled.
+        of this Department. Department membership can be extended to Groups,
+        if <span class="doc-desc-title">Alerts &amp; Notices
+        Recipients</span> includes groups members.
 
 auto_response_settings:
     title: Autoresponder Settings