docs(router): fix a typo (#2958)

Author: shairez

public/docs/ts/latest/guide/router.jade

@@ -1789,7 +1789,7 @@ h3#can-activate-child-guard <i>CanActivateChild</i>: guarding child routes
   Let's extend our `AuthGuard` to protect when navigating between our `admin` routes. First we'll open our
   `auth-guard.service.ts` and add `CanActivateChild` interface to our imported tokens from the router package.
 
-  Next, we'll implement the `canActivateChild` method with takes the same arguments as the `canActivate` method,
+  Next, we'll implement the `canActivateChild` method which takes the same arguments as the `canActivate` method,
   an `ActivatedRouteSnapshot` and `RouterStateSnapshot`. The `canActivateChild` behaves the same way the other
   guards do, returning an `Observable<boolean>` or `Promise<boolean>` for async checks and `boolean` for sync checks.
   We'll return a `boolean`