docs(cookbook/graphql): Add docregions

Author: Urigo

public/docs/_examples/heroes-graphql/ts/app/hero-detail.component.ts

@@ -28,6 +28,7 @@ export class HeroDetailComponent implements OnInit {
     private apollo: Angular2Apollo
   ) {}
 
+  // #docregion service-fetch-by-id
   ngOnInit(): void {
     this.route.params.subscribe(params => {
       const heroId = params['id'];
@@ -51,6 +52,7 @@ export class HeroDetailComponent implements OnInit {
       // #enddocregion graphql-query
     });
   }
+  // #enddocregion service-fetch-by-id
 
   // #docregion save
   save(): void {