We'll add a sprintr feedback widget in there soon, so you can send feedback about the API docs back as well!
Glad to know it's useful!
We've only started to document the full JS API as of 3.0. It's still incomplete, but all the main objects and their functions are there. We put more effort into documenting functions that are commonly used in custom widgets (and providing example code for them) than we do with functions that are obscure, ambiguous or not widely used (which we will probably deprecate in the next major release).
Documented API functions can be considered stable. If there is a change made in a next major release to these functions your code will still work because we also load a compatibility module by default.
As Robert mentioned, we will start using the feedback widget for documentation feedback. If you feel that a specific section needs more documentation or example code, use it - all feedback is welcome and will be used.