put SSO under "known limitations"

docs/installation_instructions.md

@@ -322,13 +322,19 @@ These applications should be available after the installation is completed:
 * [WordPress](https://wordpress.com), a website content management system.
   - WordPress is available at https://www.oas.example.org. Click the "Log in"
     button and then click "Login with OpenID Connect" to use the single sign-on
-    server.
+    server. Note that if you log in with the single sign-on server, you will not
+    have "admin" rights within WordPress. For that, use the admin credentials in
+    the `secrets` folder.
 * [Grafana](https://grafana.com) that shows you information about the status of
   your cluster.
   - Read more about Grafana in the [monitoring chapter below](#monitoring)
 
 ### Known limitations
 
+- Single sign-on is still in an experimental phase. We are still working on
+  transferring "roles" from users in the central database to applications, so
+  your SSO's admin user gets admin permissions in all the applications. Some
+  applications do not support logging out, currently.
 - Nextcloud does not send emails yet. You can configure sending emails by going
   to Settings -> Basic settings -> Email server and entering SMTP email
   credentials.