Ask HN: What's the best documentation you've ever read?

EDIT: It all depends on how you set the bar, though. There are plenty of projects whose entire documentation is a README with a few examples.

Also, what's "best", documentation that greatly explains a horrible, unintuitive interface of a program or one that hardly needs to exist because the use of the program is so intuitive, you don't need documentation? Greater effort was spent in the former, but you understand the program better in the latter.

If you want to do anything useful with Redux, the Redux docs are pretty terrible.

I hate any docs that are written in "step" form rather than "book/info" form.

I search for a specific thing I want to learn about and apparently it's skipped over because it's not "a commonly used thing".