In the Ruby world the most common way to generate documentation is with Yardocs. It basically generates documentation by scraping the code comments and provides a structured API for writing comments that it can interpret. For example to annotate that a parameter of a certain method is a duck type that responds to #to_s (to string), you would simply make a comment above the method definition that says: # @param parameter_name [#to_s] a parameter that responds to #to_s.

I've started the process of documenting everything (currently at 45.76% documented, according to Yard's statistics) and posting it to the Github page for the rtasklib repo, which you can access here or from the readme. Here's the documentation for the Taskrc class for example. To speed up this process I found a Python utility that does the generation, called ghp-import, which switches to the gh-pages branch, generates the docs, makes a commit, and pushes it to the repo.