Revert back to referring to go-md2man as go-md2man
    
    The 'go-md2man' virtual Provides was briefly lost after the
    golang-github-cpuguy83-go-md2man package was renamed to
    golang-github-cpuguy83-md2man.  The virtual Provides has since been
    restored [1], and go-md2man is being used as a standalone binary tool,
    not as a Go package that's imported into Toolbx's source code.  Hence,
    it makes sense to refer to the tool as go-md2man, and not by it's
    import path.
    
    This reverts commit 701836afcad6f0b08d8430e0914103d0871e4cdc.
    
    There's no need to do a build just for this.
    
    [1] golang-github-cpuguy83-md2man commit c085b15e5acd8d07
        https://src.fedoraproject.org/rpms/golang-github-cpuguy83-md2man/c/c085b15e5acd8d07