Write up developer documentation

I've noticed a pattern where projects making use of this plugin consistently run into unforeseen delays which can be traced back to misunderstandings of the basic data model used by the plugin, the functionality enabled by default, and the expected points to extend it at. This is exacerbated by the fact that it's written in an OOP style which isn't consistent with most of the Human Made libraries.

Opening this ticket as a reminder that we want to go back through this and write up solid developer documentation for future engineers who try to integrate it into custom workflows.

Leave a note of pain points to cover below:

- [ ] TK