Edit an existing docs page or PR

The failure this skill prevents: an agent asked to "fix the wording on PR 1234" cuts a fresh branch, commits there, and opens a second pull request against a teammate's work. Land edits on the branch that already exists.

Step 1. Check out the PR's own branch

When the request names a PR, by number or URL, work on that PR's head branch.

gh pr view <n> --json number,title,headRefName,baseRefName,author,isCrossRepository,files
git status --porcelain          # must be clean; stop and ask if it is not
git fetch origin <headRefName>
git checkout <headRefName>      # tracks origin/<headRefName>