state same-repo placement law; file doc-review bookend in member repo (#613)
Make the placement law explicit: each task is filed in the repo where its closing PR will land, and a PR only Closes an issue in its own repo — cross-repo links are Ref/comments, never Closes. Fix the bookend guidance so the documentation-review task (and any bookend whose PR lands in a member repo, e.g. site docs in vergil-tooling/docs/site) is filed in that member repo, not blanket .github. Prevents the mis-placement that produced a vergil-tooling PR closing vergil-project/.github#127.