code: public function onSiteSaved(SiteSavedEvent $event)
      {
          $fs = new Filesystem();
          $fs->mirror(
              $this->configurationHandler->uploadAssetsDir(),
              $this->configurationHandler->uploadAssetsDirProduction()
          );
      }
docs: Synchronizes the backend folder with the production one
  @param \RedKiteCms\EventSystem\Event\PageCollection\SiteSavedEvent $event