Add Context in review prompt (#104)

Example: 

google-gemini/logo-maker#43 (review)

google-gemini/logo-maker#61 (review)

---------

Signed-off-by: Xuejie(Alicia) Tang <tangxuejie96@163.com>

Author: aliciatang07

.github/workflows/gemini-pr-review.yml

@@ -219,7 +219,8 @@ jobs:
             3. Run: echo "${PR_NUMBER}" to get the PR number
             4. Run: echo "${ADDITIONAL_INSTRUCTIONS}" to see any specific review
                instructions from the user
-            5. Run: gh pr diff "${PR_NUMBER}" to see the full diff
+            5. Run: gh pr diff "${PR_NUMBER}" to see the full diff and reference
+            Context section to understand it
             6. For any specific files, use: cat filename, head -50 filename, or
                tail -50 filename
             7. If ADDITIONAL_INSTRUCTIONS contains text, prioritize those
@@ -346,6 +347,40 @@ jobs:
             Keep comments bodies concise and to the point.
             Keep each comment focused on one issue.
 
+            ## Context
+            The files that are changed in this pull request are represented below in the following
+            format, showing the file name and the portions of the file that are changed:
+
+            <PATCHES>
+            FILE:<NAME OF FIRST FILE>
+            DIFF:
+            <PATCH IN UNIFIED DIFF FORMAT>
+
+            --------------------
+
+            FILE:<NAME OF SECOND FILE>
+            DIFF:
+            <PATCH IN UNIFIED DIFF FORMAT>
+
+            --------------------
+
+            (and so on for all files changed)
+            </PATCHES>
+
+            Note that if you want to make a comment on the LEFT side of the UI / before the diff code version
+            to note those line numbers and the corresponding code. Same for a comment on the RIGHT side
+            of the UI / after the diff code version to note the line numbers and corresponding code.
+            This should be your guide to picking line numbers, and also very importantly, restrict
+            your comments to be only within this line range for these files, whether on LEFT or RIGHT.
+            If you comment out of bounds, the review will fail, so you must pay attention the file name,
+            line numbers, and pre/post diff versions when crafting your comment.
+
+            Here are the patches that were implemented in the pull request, per the
+            formatting above:
+
+            The get the files changed in this pull request, run:
+            "$(gh pr diff "${PR_NUMBER}" --patch)" to get the list of changed files PATCH
+
             ## Review
 
             Once you have the information, provide a comprehensive code review by:
@@ -403,6 +438,7 @@ jobs:
                 - Highlight positive aspects of the implementation
                 - Note any recurring themes across files
 
+
       - name: 'Post PR review failure comment'
         if: |-
           ${{ failure() && steps.gemini_pr_review.outcome == 'failure' }}