Add upstream Props Bot improvements.

This syncs over upstream improvements to the Props Bot example workflow.

The important change in this commit is ensuring the workflow does not run on the `issue_comment` event when a PR is not the subject of the comment. Previously, the conditions were too loose, allowing any event to run as long as `labeled` was not the action.

.github/workflows/props-bot.yml

@@ -2,25 +2,26 @@ name: Props Bot
 
 on:
   # This event runs anytime a PR is (re)opened, updated, or labeled.
-  # The logic below will look for
+  # GitHub does not allow filtering the `labeled` event by a specific label.
+  # However, the logic below will short-circuit the workflow when the `props-bot` label is not the one being added.
   pull_request:
     types:
       - opened
       - synchronize
       - reopened
       - labeled
   # This event runs anytime a comment is added or deleted.
-  # You cannot filter this event to happen for PR comments only.
+  # You cannot filter this event for PR comments only.
   # However, the logic below does short-circuit the workflow for issues.
   issue_comment:
     type:
       - created
       - deleted
-  # This event will run everytime a new PR review is created.
+  # This event will run everytime a new PR review is initially submitted.
   pull_request_review:
     types:
       - submitted
-  # This event runs anytime a PR review comment is added or deleted.
+  # This event runs anytime a PR review comment is created or deleted.
   pull_request_review_comment:
     types:
       - created
@@ -51,10 +52,16 @@ jobs:
       pull-requests: write
       contents: read
     timeout-minutes: 20
+    # The job should only run if:
+    #
+    # - A pull request review is created or commented on.
+    # - An issue comment is added to a pull request.
+    # - A pull request is opened, synchronized, or reopened.
+    # - The `props-bot` label is added to the pull request.
     if: |
       contains( fromJSON( '["pull_request_review", "pull_request_review_comment"]' ), github.event_name ) ||
       ( github.event_name == 'issue_comment' && github.event.issue.pull_request ) ||
-      github.event.action != 'labeled' ||
+      github.event_name == 'pull_request' && github.event.action != 'labeled' ||
       'props-bot' == github.event.label.name
 
     steps: