Create automatic documentation generation

[GPMueller]

Probably readthedocs.io would do nicely.

However, it should be looked into if some of the API docs can be automatically generated from the source code, in order to avoid them going out of date.

[GPMueller]

The C API could be nicely documented using https://github.com/GPMueller/clang-api-doc
This would produce docs similar to https://spirit-docs.readthedocs.io/en/latest/core/docs/c-api/API_Reference.html

The Python interface can be automatically documented, but it is ugly to do with readthedocs because we would need to build the whole ovf library. I am against doing this on this project.