Specifying initial admin user with authentication enabled is impossible / undocumented

The documentation doesn't really give a clear path forward if you have enabled authentication but don't have any admin users already set up.  You cannot use ALTER SYSTEM to add an admin user if you are not already an admin user.

It would be good if there was a way to specify admin users in drill-override.conf.  If this is already possible, it would be good to update the docs to clarify that.