docs(aio): update migrated content from anguar.io

aio/content/examples/hierarchical-dependency-injection/src/app/villains.service.ts

@@ -0,0 +1,17 @@
+import { Injectable } from '@angular/core';
+
+import { of }         from 'rxjs/observable/of';
+
+export interface Villain { id: number; name: string; }
+
+@Injectable()
+export class VillainsService {
+ villains: Villain[] = [
+    { id: 1, name: 'Dr. Evil'},
+    { id: 2, name: 'Moriarty'}
+  ];
+
+  getVillains() {
+    return of(this.villains);
+  }
+}