fix use comment for docs preview URL

Author: samuelcolvin

.github/set_docs_preview_url.py

@@ -7,6 +7,7 @@
 GITHUB_TOKEN = os.environ['GITHUB_TOKEN']
 REPOSITORY = os.environ['REPOSITORY']
 PULL_REQUEST_NUMBER = os.environ['PULL_REQUEST_NUMBER']
+REF = os.environ['REF']
 
 m = re.search(r'https://(\S+)\.workers\.dev', DEPLOY_OUTPUT)
 assert m, f'Could not find worker URL in {DEPLOY_OUTPUT!r}'
@@ -42,6 +43,10 @@
 
 <table>
 <tr>
+<td><strong>commit:</strong></td>
+<td><code>{REF:.7}</code></td>
+</tr>
+<tr>
 <td><strong>Preview URL:</strong></td>
 <td><a href="{preview_url}">{preview_url}</a></td>
 </tr>

.github/workflows/after-ci.yml

@@ -94,3 +94,4 @@ jobs:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
           REPOSITORY: ${{ github.repository }}
           PULL_REQUEST_NUMBER: ${{ github.event.workflow_run.pull_requests[0].number }}
+          REF: ${{ github.event.workflow_run.head_sha }}