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

aio/content/examples/structural-directives/src/app/hero.ts

@@ -0,0 +1,13 @@
+// #docregion
+export class Hero {
+  id: number;
+  name: string;
+  emotion?: string;
+}
+
+export const heroes: Hero[] = [
+  { id: 1, name: 'Mr. Nice',  emotion: 'happy'},
+  { id: 2, name: 'Narco',     emotion: 'sad' },
+  { id: 3, name: 'Windstorm', emotion: 'confused' },
+  { id: 4, name: 'Magneta'}
+];