docs: move package host admin docs to other code host docs
Created by: mrnugget
This is the 2nd step of what I started yesterday: it splits the docs into two. Into "integration" docs and "how to setup a code host connection".
That mirrors what we've done for the other code hosts. It's not perfect and I think there's still a lot of other improvements to be made, but I think consistency is already helpful here.
Test plan
- Tested locally after running
sg run docsite