See #248: changelog

changes/changelog.d/248.feature

+New invite system (#248)
+
+
+New invite system
+^^^^^^^^^^^^^^^^^
+
+On closed instances, it has always been a little bit painful to create accounts
+by hand for new users. This release solve that by adding invitations.
+
+You can generate invitation codes via the "users" admin interface (you'll find a
+link in the sidebar). Those codes are valid for 14 days, and can be used once
+to create a new account on the instance, even if registrations are closed.
+
+By default, we generate a random code for invitations, but you can also use custom codes
+if you need to print them or make them fancier ;)
+
+Invitations generation and management requires the "settings" permission.