add graphviz graph of OBS repository relationships
add graphviz graph of OBS repository relationships

This allows us to use the https://www.gravizo.com service to embed an
automatically rendered version of this graph into Markdown
documentation within GitHub, without having to worry about rendering
it ourselves.

This needs to be in a public GitHub repository in order for
http://www.gravizo.com/ to be able to read it.

gosipyan/automation,gosipyan/automation,aspiers/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,SUSE-Cloud/automation,aspiers/automation,aspiers/automation,aspiers/automation,SUSE-Cloud/automation,gosipyan/automation,gosipyan/automation