Merge pull request #2133 from obra/fix/review-base-sha-merge-base

fix(requesting-code-review): anchor the multi-commit BASE_SHA alternative to the merge base

skills/requesting-code-review/SKILL.md

@@ -25,7 +25,7 @@ Dispatch a code reviewer subagent to catch issues before they cascade. The revie
 
 **1. Get git SHAs:**
 ```bash
-BASE_SHA=$(git rev-parse HEAD~1)  # or origin/main
+BASE_SHA=$(git rev-parse HEAD~1)  # or: git merge-base origin/main HEAD
 HEAD_SHA=$(git rev-parse HEAD)
 ```