message: docs: align `toh-pt5` code with `toh-pt4`
  This commit aligns the code of `HeroService` `getHeroes()` and
  `getHero()` methods in `toh-pt5` with that of `toh-pt4`. I.e. it applies
  the changes from to `toh-pt5`.
  PR Close
diff: @@ -12,16 +12,16 @@ export class HeroService {
  constructor(private messageService: MessageService) { }
  getHeroes(): Observable<Hero[]> {
  - // TODO: send the message _after_ fetching the heroes
  + const heroes = of(HEROES);
  this.messageService.add('HeroService: fetched heroes');
  - return of(HEROES);
  + return heroes;
  }
  // #docregion getHero
  getHero(id: number): Observable<Hero> {
  - // TODO: send the message _after_ fetching the hero
  + const hero = HEROES.find(h => h.id === id);
  this.messageService.add(`HeroService: fetched hero id=${id}`);
  - return of(HEROES.find(hero => hero.id === id));
  + return of(hero);
  }
  // #enddocregion getHero
  }
  