If you are interested in the current status, see the 'docs' topic branch.
You will see there some work products, particularly a marked up copy of the old manual, with my thoughts about what needs to be done, and a ledger of exported symbols, which should be documented in the manual.
Comments and suggestions welcomed. Patches also welcomed, but for that perhaps it's best you contact me. I'd be happy to cede parts of the manual to others.
Best, r