Allow deploy keys to commit to the doc git repository of a project
    
    While stored in a different git repo, docs are part of the sources of
    a project and should not contain any privileged information unlike
    the tickets or requests git repositories.
    Thus we are fine with granting commit access to deploy keys to the
    doc git repository.
    
    Fixes https://pagure.io/pagure/issue/4763
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>