[bdbarnett]

The Reference section is now written from the type stubs. Each module's names, constructors, options and constants on the Reference pages come from its .pyi, so the docs and your editor's completion can't drift apart. This PR is stacked on #404 (the stubs) and targets its branch; retarget it to main once that merges.

The existing pages keep their file names and headings, so every link to them still works, including the #audiobiquad and #audioroutemidside anchors. Their hand-written module sections are now generated, with the prose that a user needs moved into the stubs' docstrings (the constructor table for the biquad stays as a short hand-written table). Two new pages, Mixing and routing and Analysis and utilities, cover the modules that had no page, and the pump and Vorbis pages gain a generated names section. The docs had never been built with Sphinx here, so this also adds docs/conf.py, a requirements file, .readthedocs.yaml and a Docs workflow that builds with warnings as errors. Making that build pass meant pointing links to folders and files outside docs/ at GitHub and fixing eight heading jumps in the upstream reports.

I built the site with sphinx-build -W --keep-going with and without network and it finishes with no warnings; all 25 modules render. I didn't build it on Read the Docs, and I haven't read every generated page for wording.