Has anyone here ever used/contributed to it?
For me it the answer is no and no, while I read about it once or twice, probably when it was introduced, I totally forgot about it afterwards and never even visited it by accident.
I once tried to contribute to StackOverflow docs, very early in it’s life cycle, by trying to make a docs version of https://www.junglecoder.com/blog/PerformanceGotchasBindingList. My thought was that since MSDN covers the vast majority of the basic uses cases for most C#/WinForms related things, that providing examples of a corner case like that might be appreciated.
It was there for a little bit, but was ultimately removed from the C# docs topic without a suggestion as to where it might be on topic. I know the information itself is useful, as it’s the only article I’ve written that has gotten more than one comment from strangers on the internet.
I’ll admit that I wasn’t a very active use of Stack Overflow docs, but after that got removed, I kinda just decided to pass on trying to contribute to it much, since the sort of stuff I’d want to add might not even be on topic. Looking at the docs now, it mostly looks like it is information that is covered pretty well elsewhere.
One thing that Q&A has that docs don’t is that Q&A is meeting needs that people do have. Docs, at this point, doesn’t seem to have a clear line in that regard.