All the docs should be in this repo (not just "end user docs") about docs

[dewitt]

+1

At least for a while, the end-user/developer/operator/contributor roles are going to be blurred, so let's just make it easy for people to find everything they're looking for. This is consistent with the real-world experience we've seen when onboarding early customers as well.

Recommend moving everything from design docs to user docs to the same place (here).

[evankanderson]

I'd like to keep at least docs/spec in the knative/serving, so that e.g. knative/serving#1296 can update both spec and implementation at the same time. (So that we can see the impact of the spec change on the implementation when considering the implementation.)

[evankanderson]

The container contract should probably also live in knative/serving, I think, with a summary in this repo.

[rgregg]

build docs moved over already.