message: docs: Add selector for `PeekABooDirective`
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diff: @@ -5,7 +5,7 @@ import { LoggerService } from './logger.service';
  let nextId = 1;
  // #docregion ngOnInit
  -@Directive()
  +@Directive({selector: '[appPeekABoo]'})
  export class PeekABooDirective implements OnInit {
  constructor(private logger: LoggerService) { }
  