document limitations of WP SSO

docs/usage.rst

@@ -145,3 +145,15 @@ WordPress
 ~~~~~~~~~
 
 `WordPress <https://wordpress.com>`__ is a website content management system.
+
+Known issues
+''''''''''''
+
+If you want admin privileges inside WordPress, you need to set this in the
+Dashboard. Then, you need to log into WordPress again.
+
+If this is your first time logging into WordPress, you have to log out and in
+again for your admin privileges to be applied.
+
+For more information and technical details, refer to `the issue in our issue
+tracker <https://open.greenhost.net/stackspin/wordpress-helm/-/issues/97>`__.