3rd party repos policy: merge wiki material
    
    At some point in the past, a more elaborate 3rd party repos
    policy was approved and recorded on the Workstation wiki pages:
    
    https://fedoraproject.org/wiki/Workstation/Third_party_software_Workstation_Guidelines
    
    The wiki page is more detailed than the FESCo policy and contains some useful
    guidance. It also applies to all Fedora editions. It therefore makes sense to
    merge the wiki version into fesco-docs.
    
    Three notable changes:
    
     - The previous version of the FESCo policy stated that 3rd party repos containing
    free software must be approved by FESCo and Fedora Legal, whereas non-free
    repos can be approved by working groups. The new version states that working groups
    can approve either type of repo.
     - The existing metadata rules for full 3rd party repos are applied to other repo
    types, including Coprs.
     - The wiki policy covers which type of repos can be used as the main repos of a
    Fedora edition. Since these aren't 3rd party repos per se, these parts of the
    policy have been excluded.