docs(architecture): update wording (angular#3049)

Author: jvandemo

public/docs/ts/latest/guide/architecture.jade

@@ -432,7 +432,7 @@ figure
 +makeExcerpt('app/logger.service.ts', 'class')
 
 :marked
-  Here's a `HeroService` that fetches heroes and returns them in a resolved !{_PromiseLinked}.
+  Here's a `HeroService` that uses a !{_PromiseLinked} to fetch heroes.
   The `HeroService` depends on the `Logger` service and another `BackendService` that handles the server communication grunt work.
 
 +makeExcerpt('app/hero.service.ts', 'class')