fix(docs): Tweak some grammar and add some links relating to DI.

docs/content/tutorial/step_07.ngdoc

@@ -46,8 +46,8 @@ history (back and forward navigation) and bookmarks.
 
 ### A Note About DI, Injector and Providers
 
-As you noticed the dependency injection is the core feature of AngularJS, so it's important for you
-to understand a thing or two about how it works.
+As you {@link tutorial/step_05 noticed}, {@link guide/di dependency injection} is the core feature of
+AngularJS, so it's important for you to understand a thing or two about how it works.
 
 When the application bootstraps, Angular creates an injector that will be used for all DI stuff in
 this app. The injector itself doesn't know anything about what `$http` or `$route` services do, in