Org-mode has all three of:

1. Spec, written after the fact, not by a core dev.

2. Live help in 'org-info'.

3. Elisp string extraction via 'M-x describe-function' and the like.

Difficulties arise from subtle inconsistencies between the three, and inability of any one to comprehend the kitchen-tool-bin jumble of low- and high-level functionality that has been added over the years.

OTOH, content display is economical of eye and finger effort, and some of the Emacs interaction features startingly powerful.

I wrote my own, use-case specific converter to expand org-format to HTML. Runs on the CL, written in Go.