docs: review_requested and review_request_removed to issues_timeline.go

Author: jbrill

github/issues_timeline.go

@@ -97,6 +97,14 @@ type Timeline struct {
 	//     reviewed
 	//       The pull request was reviewed.
 	//
+	//     review_requested
+	//       The actor requested a review from a user or team.
+	//       Reviewer or Requester will be populated.
+	//
+	//     review_request_removed
+	//       The actor removed a review request from a user or team.
+	//       Reviewer or Requester will be populated.
+	//
 	//     subscribed
 	//       The actor subscribed to receive notifications for an issue.
 	//