add update timestamp

.github/workflows/spelling-check-bot.yml

@@ -32,7 +32,7 @@ jobs:
       - name: Report issues
         if: env.OUTPUT != ''
         run: |
-          log_data=$(cat<<EOM
+          comment_body=$(cat<<EOM
           Typos and unknown words:
 
           ~~~
@@ -43,14 +43,15 @@ jobs:
           > To exclude words from the spellchecker, you can add valid words (web technology terms or abbreviations) to the [terms-abbreviations.txt](https://github.com/mdn/content/blob/main/.vscode/terms-abbreviations.txt) dictionary for IDE autocompletion. To ignore strings that are not words (\`AABBCC\` in code, for instance), you can add them to [ignore-list.txt](https://github.com/mdn/content/blob/main/.vscode/ignore-list.txt).
           EOM
           )
+          comment_body+=$'\n\n'$(echo "(comment last updated: $(date +'%Y-%m-%d %H:%M:%S'))")
 
           gh api \
             --method PATCH \
             -H "Accept: application/vnd.github+json" \
             -H "X-GitHub-Api-Version: 2022-11-28" \
             /repos/mdn/content/issues/35634 \
             -f "state=open" \
-            -f "body=${log_data}"
+            -f "body=${comment_body}"
         env:
           OUTPUT: ${{ env.OUTPUT }}
           GH_TOKEN: ${{ github.token }}