Added additional copy

app/templates/views/invite-user.html

@@ -30,6 +30,9 @@
         error_message_with_html=True
       ) }}
     {% endif %}
+    <p>
+      Team members must be invited directly using their .gov email address, not from forwarded invitations. Invitation links to create a Notify.gov account are active for only 24 hours. Expired invitations can e re-sent from the Team members page.
+    </p>
 
     {% include 'views/manage-users/permissions.html' %}