I often find official documentation difficult to follow, and generally find myself on "other" sites looking for 'real' examples. I'm sure there are others who are quite comfortable with official docs and I guess it also differs greatly depending on the software in question.

I'd find a living document very helpful for many reasons. I've not asked many questions on SF but of those I have asked a couple of times I've felt that actually all I'm really after is a better example of how something is done, or I've followed a guide without really understanding what I'm doing, because the person writing the guide did understand each step.

Would you still have people asking questions that are 90% the same as something in a document and only 10% unique? Yes, but answers to those questions could increase the quality of the documentation. I might add an answer on topic x, but not have a complete understanding of the topic. Yet I could contribute a good example to the document, or someone else might take my answer and decide it is worthwhile putting in the document.

As for keeping things up to date, perhaps something like tags for version numbers. So you could search application + ver + search term. When a new version is released a tag just gets added to say yes this is still how it works for this version. If it changes, a document is created with the changes and the new version added.