This commit is intended to improve new user's first-interaction with the Sphinx site:
- Make page header icon/text smaller and not capitalized
- Give min-width to left sidebar (it was getting too small at certain window sizes)
- Replace features list on landing page with admonition boxes, with adaptive layout
- Add landing page "used by" section
- Slightly restructure the Extension section, into Tutorials and How-tos
- Add code to `conf.py` to write HTML write redirect pages for moved documents
- Improve support page, by adding link to Stackoverflow, GH discussion and ReadtheDocs,
and remove defunct link to libera chat and matplotlib tutorial
I missed that there are actually two sections explaining extensions in the docs and just saw the examples based one. This lead to me thinking "kind of lousy documentation, but that's probably par for the course". Would there have been a pointer to the detailed extension API description it would have saved me hours of guesswork.
