message: docs: replace unused variable by _
  replace unused variable by _  to keep the code consistent between examples
  PR Close
diff: @@ -40,7 +40,7 @@ export class HeroService {
  // #enddocregion getHeroes-1
  .pipe(
  // #enddocregion getHeroes-2
  - tap(heroes => this.log('fetched heroes')),
  + tap(_ => this.log('fetched heroes')),
  // #docregion getHeroes-2
  catchError(this.handleError('getHeroes', []))
  );
  