message: docs(router): add RxJS filter pipe operator to example
  This example for Angular 6 requires piping the RxJS filter operator in order to traverse the multitude of Router Events.
  PR Close
diff: @@ -33,7 +33,9 @@ export type NavigationTrigger = 'imperative' | 'popstate' | 'hashchange';
  * ```
  * class MyService {
  * constructor(public router: Router, logger: Logger) {
  - * router.events.filter(e => e instanceof RouterEvent).subscribe(e => {
  + * router.events.pipe(
  + * filter(e => e instanceof RouterEvent)
  + * ).subscribe(e => {
  * logger.log(e.id, e.url);
  * });
  * }
  