Document the need for Admin privileges

For most major task, our user account suffice on OBS. But there are certain exceptions, like creating new repositories, wherein we need Admin level privileges.

This is required when we create new repositories for a stable release: security, updates, backports.

Document this oddity that the user needs to have Admin level privileges

Signed-off-by: Ritesh Raj Sarraf ritesh.sarraf@collabora.com