Autogenerate documentation about hooks available for plugins

[yuvipanda]

Our hooks exist in tljh/hooks.py, and have docstrings. We should autogenerate a reference page from here.

[consideRatio]

This should perhaps be done using autodoc_traits as done in various other projects in our GitHub org.

We currently don't have a reference section in our docs, I think we should add such autogenerated docs there, and that we should also add autogenerated reference docs about the config options from a JSON schema there if #725 is implemented.