Modernize Modelforge CI about modelforge

[vmarkovtsev]

@smola How do we upload the autogenerated documentation for this project?

I mean we can use ReadTheDocs but we also have /docs.

[smola]

@vmarkovtsev /docs should be for gitbook (see gitbase) as example.
For autogenerated docs, at the moment we have docsrv to generate and serve them (see engine example).

[vmarkovtsev]

@smola What are our exact steps to serve the autogenerated Modelforge docs at sourced.tech?

[vmarkovtsev]

As discussed with @smola docs are postponed until https://github.com/src-d/feature-idea/issues/59