New theme: sphinx-immaterial

[dolfinus]

sphinx-material theme is not being updated since 2021. It's actually quite old fork of mkdocs-material theme, and the divergence happened a long time ago.

The most recent fork of original theme is now a sphinx-immaterial. It is actively maintained, and has a lot of new features missing in sphinx-material. https://jbms.github.io/sphinx-immaterial/

Example of a project which uses this theme: galois https://galois.readthedocs.io/en/latest/

It will be great if this new there will be added to sphinx-themes. And maybe even replace outdated sphinx-material