…r mkdocs. Add mkdocs.yml with proper configuration, enable automated generation of the doc API from the docstring, and start converting a few pages (index, getting started, developers) for demo.

… docs using pytest-markdown-docs. Needed to comment 1 small test that seemingly should fail (AttributeError: DefinedNamespace like object has no attribute '_NS', indeed the DefinedNamespace class expect a _NS, so it makes sense it fails) but for some reason it was not properly failing when ran with regular pytest, but it fails with pytest-markdown-docs

…to markdown with google style, updated config for mkdocs (readthedocs, tox, task)

fixed #3128

…odeblock testing