[osivertsson]

The big gain is that is all just text and can be handled very well by the same version control system as the code is.

I can easily glance at what has happened to the docs just by looking at a diff, much like I do with all code my team produces already.

And being represented by all text doesn't mean this is what you give your customers. With a bit of work with pandoc etc. you can get a really slick and impressive end result.