Move to mkdocs

[Nicholas Car]

Dear RDFLib community,

Thanks to lots of hard work by Vincent Emonet (https://github.com/vemonet) we have migrated our 8.x branch (main) to using mkdocs for documentation, rather than Sphinx.

We decided to do this because mkdocs is more familiar to current Python developers, uses simpler Markdown instead of ReST and is fully supported by ReadTheDocs.

You can see the rendering of mkdocs at our ReadTheDocs latest: https://rdflib.readthedocs.io/en/latest/

We still maintain the Sphinx documentation for stable - https://rdflib.readthedocs.io - and for 7.x releases: https://rdflib.readthedocs.io/en/7.1.4/

We will probably make the style of the mkdocs documentation match our current/legacy colour scheme a bit more soon.

So please have consider adding lots of lovely documentation for all the many functions and modules that still don't have it, such as the Dataset graph() function, https://rdflib.readthedocs.io/en/latest/apidocs/rdflib.graph/#rdflib.graph.Dataset.graph, and the parse_patch.py example, https://rdflib.readthedocs.io/en/latest/apidocs/examples.parse_patch/#examples.parse_patch.

Cheers, Nick