What does Google (or others) use for an intranet or team documentation? We're using Quip and it is just a black hole where documents go to die, never be seen again no matter how badly you want to find it.
Pros: Get's checked in like code, gets reviewed, and leaves a nice paper trial of edits.
Cons: Doesn't invite comments/discussions as well as Docs does.
I can imagine that can quickly become a fulltime job though. Still, a formal role of documenter / archivist in a bigger software endeavour should be considered.