Update README.md (#41)

Suggest the specific `git log` command to run to ensure only commits that are included by the PR are considered.

README.md

@@ -53,10 +53,10 @@ jobs:
           openai-api-key: ${{ secrets.OPENAI_API_KEY }}
           prompt: |
             This is PR #${{ github.event.pull_request.number }} for ${{ github.repository }}.
-            Base SHA: ${{ github.event.pull_request.base.sha }}
-            Head SHA: ${{ github.event.pull_request.head.sha }}
 
-            Review ONLY the changes introduced by the PR.
+            Review ONLY the changes introduced by the PR, so consider:
+               git log --oneline ${{ github.event.pull_request.base.sha }}...${{ github.event.pull_request.head.sha }}
+
             Suggest any improvements, potential bugs, or issues.
             Be concise and specific in your feedback.