Add tomldoc-generated documentation

This uses my new tool https://gitlab.com/TheZoq2/tomldoc to generate documentation for the config format. It's not great at the moment, because we are missing docstrings for a lot of our configs, and because we have more structs that are usually inlined than I had in mind when I wrote tomldoc.

You can see a more well documented thing at https://docs.spade-lang.org/swim_project_configuration/config__Config.html

My plan is to set up a CI flow thing that automatically pulls the docs from this into https://gitlab.com/surfer-project/docs so we can have docs.surfer-project.org