install containerfile and dockerfile manpages
    
    Along with this change:
    
    the podman package should get rid of:
    `Dockerfile.5.gz`
    `dockerignore.5.gz`
    `.dockerignore.5.gz`
    
    the buildah package should get rid of:
    `Containerfile.5.gz`
    `containerignore.5.gz`
    `.containerignore.5.gz`
    
    Signed-off-by: Lokesh Mandvekar <lsm5@fedoraproject.org>