Research how to generate API Sphinx docs from OpenAPI/Swagger

[lunkwill42]

The API documentation in Sphinx is currently manually maintained in parallel with the autogenerated Swagger docs. This should be unnecessary, as its best to maintain the documentation as close to the API definitions as possible. The current way of doing this is pretty much guaranteed to result in outdated documentation.

[hmpf]

I found sphinxcontrib-openapi, not tested.

[hmpf]

Our schema needs to be improved a little, the "spectacular" management command has some complaints, I'll open a new issue.