docs: update @Injectable section

aio/content/guide/dependency-injection-in-action.md

@@ -17,8 +17,8 @@ in the `@Injectable()` decorator of the service itself.
 <code-example path="dependency-injection/src/app/heroes/hero.service.3.ts" title="src/app/heroes/hero.service.3.ts" linenums="false">
 </code-example>
 
-`providedIn` here tells Angular that the root injector is responsible for creating an instance of `HeroService`
-and making it automatically be made available to the entire 
+`providedIn` here tells Angular that the root injector is responsible for creating an instance of `HeroService`.
+Services provided this way are automatically available to the entire 
 application and don't need to be listed in any module.
 
 
@@ -475,7 +475,7 @@ If the search is futile, the injector throws an error&mdash;unless the request w
 A new injector has no providers.
 Angular initializes the injectors it creates with some providers it cares about.
 You have to register your _own_ application providers manually,
-usually in the `@Injectable` decorator of the service, `providers` array of the `Component` or `Directive` metadata:
+usually in the `@Injectable` decorator of the service, `providers` array of the `NgModule` or `Directive` metadata:
 
 <code-example path="dependency-injection-in-action/src/app/app.component.ts" region="providers" title="src/app/app.component.ts (providers)">
 
@@ -493,7 +493,7 @@ The simple way of defining providers in the `@Injectable` decorator of the class
 <code-example path="dependency-injection/src/app/heroes/hero.service.0.ts" title="src/app/heroes/hero.service.0.ts" linenums="false">
 </code-example>
 
-Another alternative is to mention the class in the providers array and you're done.
+Another alternative is to mention the class in the providers array of the `@NgModule` and you're done.
 
 <code-example path="dependency-injection-in-action/src/app/hero-bios.component.ts" region="class-provider" title="src/app/hero-bios.component.ts (class provider)" linenums="false">