Archive Pagure repository and redirect to GitLab
    
    This commit removes all files in the repository that are now hosted in
    other git repositories. It also adds clear information about next steps
    in this Pagure repository.
    
    To conclude the GitLab migration, we will achieve zero open issues on
    the Mindshare Pagure repo and then set it to read-only status. Any new
    issues should be closed and manually copied to GitLab by a Committee
    member.
    
    Part of #370.
    
    Signed-off-by: Justin W. Flory (he/him) <jwf@redhat.com>