I'm currently working getting a base level of documentation out. I created an API documentation generator and generated API docs. Those are now available. https://joshclose.github.io/CsvHelper/api
I'm going to look into DocFX and see if I can bend it to fit how I want my docs to behave. It has a lot of good things already built into it, like merging content such as examples in with the API docs. I'm going to do some of GeertvanHorrik's pull requests first though.