File _service of Package gtk-doc

<services>
  <service name="tar_scm">
    <param name="url">https://github.com/eweOS/packages.git</param>
    <param name="revision">gtk-doc</param>
    <param name="scm">git</param>
    <param name="extract">*</param>
  </service>
  <service name="download_files" />
</services>