Add callback URL to upgrade guidelines

docs/more/self-hosted-dsw/upgrade-guidelines.rst

@@ -43,12 +43,16 @@ Usually, nothing special is required for the upgrade. Internal structure changes
 
    Make sure to stop ``document-worker`` and ``mailer`` before upgrading to the next version. Run ``wizard-server`` first, then run the workers. Otherwise the database migrations might not work correctly.
 
-3.28.X to 4.0.0
+3.28.X to 4.0.X
 ---------------
 
-- **(breaking)** Client runs on nested route ``/wizard``, and server runs on nested route ``/wizard-api``. These changes must be reflected in the deployment configuration (such as routing in a reverse proxy) and ``clientUrl`` in the :ref:`config-server`.
+- **(breaking)** The client runs on the nested route ``/wizard``, and the server runs on the nested route ``/wizard-api``. These changes must be reflected in the deployment configuration (such as routing in a reverse proxy) and the ``clientUrl`` in the :ref:`config-server`.
 - **(breaking)** :ref:`client-configuration` for a custom logo and theme no longer uses SASS and needs to be updated accordingly.
 - **(breaking)** :ref:`api-keys` created in previous versions will no longer work.
+- **(breaking)** The callback URL for :ref:`OpenID <auth-services>` (such as Google or Life Science Login) has changed due to the nested route, so it has to be set up, for example:
+
+  - Before: ``https://researchers.ds-wizard.org/auth/google/callback``
+  - After: ``https://researchers.ds-wizard.org/wizard/auth/google/callback``
 
 3.27.X to 3.28.X
 ----------------