Include more information in the GitHub review body (#24)

Also drop the automated review message from the text representation of
the review. It's pretty obvious that it's automated in that context.

rosdistro_reviewer/review.py

@@ -136,9 +136,11 @@ def summarize(self) -> str:
         if not self._elements:
             return '(No changes to supported elements were detected)'
 
-        message = 'This is an automated review.'
-        for element, criteria in self.elements.items():
-            message += f'\n\nFor changes related to {element}:'
+        message = ''
+        for idx, (element, criteria) in enumerate(self.elements.items()):
+            if idx:
+                message += '\n\n'
+            message += f'For changes related to {element}:'
             for criterion in criteria:
                 message += '\n* ' + criterion.recommendation.as_symbol()
                 message += ' ' + textwrap.indent(criterion.rationale, '  ')[2:]

rosdistro_reviewer/submitter/github.py

@@ -16,6 +16,12 @@
 GITHUB_TOKEN_ENVIRONMENT_VARIABLE = EnvironmentVariable(
     'GITHUB_TOKEN', 'Authentication token secret for GitHub')
 
+BODY_HEADER = """Hi there, thanks for contributing to ROS!
+
+This is an automated review generated by the [rosdistro-reviewer tool](https://github.com/ros-infrastructure/rosdistro-reviewer). If you'd like the tool to run again, just [re-request review from GitHub Actions](https://github.com/ros-infrastructure/rosdistro-reviewer?tab=readme-ov-file#running-rosdistro-reviewer-in-github-actions).
+
+"""  # noqa: E501
+
 
 class GitHubSubmitter(ReviewSubmitterExtensionPoint):
     """Submit reviews to GitHub pull requests."""
@@ -86,6 +92,6 @@ def _annotation_to_comment(
         recommendation = review.recommendation
 
         pr.create_review(
-            body=message,
+            body=BODY_HEADER + message,
             event=RECOMMENDATION_EVENTS[recommendation],
             comments=comments)