docs: update an example in the RouterEvent description (#50526)

PR Close #50526

packages/router/src/events.ts

@@ -58,7 +58,7 @@ export const enum EventType {
  * class MyService {
  *   constructor(public router: Router) {
  *     router.events.pipe(
- *        filter((e: Event): e is RouterEvent => e instanceof RouterEvent)
+ *        filter((e: Event | RouterEvent): e is RouterEvent => e instanceof RouterEvent)
  *     ).subscribe((e: RouterEvent) => {
  *       // Do something
  *     });