docs: prefer upstream PR branches in code review guidance

[enyst]

Summary

• add guidance to validate docs against referenced upstream PR branches
• update verification example to include cloning PR head branches

Testing

• Not run (docs-only guidance)

[all-hands-bot]

Taste Rating: 🟡 Acceptable - Solves a real problem (false positive reviews when docs match upstream PRs) with a simple solution. Minor clarity issues that could confuse readers.

Verdict: ✅ Worth merging after addressing the inconsistency

Key Insight: The grep example contradicts the new guidance by still searching the main branch instead of the PR branch.

[all-hands-bot]

Taste Rating: 🟡 Acceptable - Solves a real problem (false positive reviews when docs correctly match upstream PRs) with a straightforward solution. One minor clarity improvement suggested.

Verdict: ✅ Worth merging after addressing the ambiguity, or merge as-is if you think the instruction is clear enough.

Key Insight: The "replace" instruction could be misread as "edit this file" rather than "run this command instead of that one."

[all-hands-bot]

Taste Rating: 🟡 Acceptable - Solves a real workflow problem (false positive reviews when docs correctly match upstream PRs) with a straightforward solution.

Verdict: ✅ Ready to merge

Key Insight: Pragmatic documentation fix that aligns reviewer behavior with the actual sync workflow - check the right source of truth when docs intentionally lead upstream changes.