Add docs

[oleksandr-pavlyk]

This PR adds initial docs and workflow to build/render it.

[oleksandr-pavlyk]

For pull-requests, like this one, documentation is rendered and uploaded as workflow's artifact (see "Build mkl_random documentation" workflow). The artifact is a ZIP archive which contains rendered documentation pages. Unarchive it, and open index.html in your browser.

Once this PR is merged into main branch, this copy is going to be pushed to gh-pages branch, and it should becomes visible at https://intelpython.github.com/mkl_random

It usually takes a couple of minutes after push to gh-pages before content is transferred to the HTTP server.

[ndgrigorian]

All seems to render correctly, artifact works, LGTM!