docs: fix typo (#2824)

public/docs/ts/latest/guide/dependency-injection.jade

@@ -257,7 +257,7 @@ block ctor-syntax
   We can either register a provider within an [NgModule](ngmodule.html) or in application components
 
   ### Registering providers in an NgModule
-  Here's our AppModule where we register a `Logger`, an `UserService`, and an `APP_CONFIG` provider.
+  Here's our AppModule where we register a `Logger`, a `UserService`, and an `APP_CONFIG` provider.
 
 - var stylePattern = { otl: /(providers)/ };
 +makeExample('dependency-injection/ts/app/app.module.ts', 'ngmodule','app/app.module.ts', stylePattern)(format='.')