docs(router): remove invalid jsdoc tags (#14097)

The `@selector` tags are not valid.
Dgeni should be able to extract this information
from the directive annotation metadata.

modules/@angular/router/src/directives/router_link.ts

@@ -72,7 +72,6 @@ import {UrlTree} from '../url_tree';
  * Then the following link `<a [routerLink]="['/user/jim']">Jim</a>` will generate the link
  * `/user/(jim//aux:team)`.
  *
- * @selector ':not(a)[routerLink]'
  * @ngModule RouterModule
  *
  * See {@link Router.createUrlTree} for more information.
@@ -132,7 +131,6 @@ export class RouterLink {
  *
  * See {@link RouterLink} for more information.
  *
- * @selector 'a[routerLink]'
  * @ngModule RouterModule
  *
  * @stable

modules/@angular/router/src/directives/router_link_active.ts

@@ -73,7 +73,6 @@ import {RouterLink, RouterLinkWithHref} from './router_link';
  * This will set the active-link class on the div tag if the url is either '/user/jim' or
  * '/user/bob'.
  *
- * @selector ':not(a)[routerLink]'
  * @ngModule RouterModule
  *
  * @stable

modules/@angular/router/src/directives/router_outlet.ts

@@ -32,7 +32,6 @@ import {PRIMARY_OUTLET} from '../shared';
  *   (activate)='onActivate($event)'
  *   (deactivate)='onDeactivate($event)'></router-outlet>
  * ```
- * @selector 'a[routerLink]'
  * @ngModule RouterModule
  *
  * @stable