Temporarily fix docs

[basnijholt]

This is not a proper fix but before I discovered how to fix it correctly this might do.

After this plot.ly and HoloMaps will correctly show.

[akhmerov]

Please add the license to the file.

[akhmerov]

Is it possible to verify this works without building locally? Is there a preview on rtd?

[basnijholt]

I just build it locally but I removed most files to speed it up.
I remove everything in docs/source/tutorial/ but tutorial.learnerND.rst, everything in docs/source/reference/, and docs/source/docs.rst.

Because the LearnerND tutorial has HoloMaps and plotly plots.