message: docs(router): mark title strategy as injectable
  Add the `@Injectable` decorator in the title strategy example so that it can be injected in the providers of the routing module.
  PR Close
diff: @@ -40,6 +40,7 @@ export class ResolvedChildATitle implements Resolve<string> {
  // #docregion custom-page-title
  +@Injectable({providedIn: 'root'})
  export class TemplatePageTitleStrategy extends TitleStrategy {
  constructor(private readonly title: Title) {
  super();
  