Which projects have excellent documentation?

I continuously research how to improve the documentation that I write and how others perceive it. But what better way than to step back for a moment and see how others have done it? But surely I am biased by now. I have adopted my own style and tend to favor projects that use that same style.

So I decided to ask Twitter instead.

Dear #lazyweb: what is the _best_ documentation that you have ever read? Which gave you the feeling that you were winning?

— Mike van Riel (@mvriel) July 10, 2014

The results were rather varying and interesting; so without further delay I present you the list of projects (in alphabetical order) whose documentation has been chosen to be above average, or even plain awesome. Almost every project has been voted for only once; for those projects that received multiple votes the number is shown behind the name in parenthesis.

It is interesting to see how many projects were selected and that there is so little overlap in the votes. With this list I can research what these have in common and what makes them so awesome.

Do you know of any other awesome documentation sites? Want to add your vote to any of the documentation pages above? Please tweet it to me, I am @mvriel on twitter.