You can just hang out on an IRC channel for a project for weeks and get a lot of ideas about how things work. Also, if we pitch documentation bounties the same way we do bug bounties, we'd probably have a lot better documentation for software projects. And if your project moves so fast documentation falls behind often, perhaps your project needs to redefine its core features enough or at least mark what is experimental and shouldn't be relied upon too much for production code. None of this stuff really needs someone to be anything more than familiar with general coding concepts. Heck, just hire some random person out of a coding academy and they can document as a way to learn the internals of a project for a while - not a lot of harm can be done to a codebase by documenting it, right?
