chore: update sample notification title format

Author: bang9

sample/ios/NotificationService/NotificationService.m

@@ -20,6 +20,7 @@ @implementation NotificationService
 - (void)didReceiveNotificationRequest:(UNNotificationRequest *)request withContentHandler:(void (^)(UNNotificationContent * _Nonnull))contentHandler {
   self.contentHandler = contentHandler;
   self.bestAttemptContent = [request.content mutableCopy];
+  self.bestAttemptContent.title = [NSString stringWithFormat:@"[RN]%@", self.bestAttemptContent.title];
   self.contentHandler(self.bestAttemptContent);
   [NotifeeExtensionHelper populateNotificationContent:request
                                           withContent: self.bestAttemptContent