docs(beta-4): update quickstart ts to include typings

public/docs/_examples/quickstart/ts/app/main.ts

@@ -1,4 +1,5 @@
 // #docregion
+///<reference path="../node_modules/angular2/typings/browser.d.ts"/>
 import {bootstrap}    from 'angular2/platform/browser'
 // #docregion app-component
 import {AppComponent} from './app.component'

public/docs/ts/latest/quickstart.jade

@@ -203,12 +203,15 @@ code-example(format="").
 +makeExample('quickstart/ts/app/main.ts', null, 'app/main.ts')(format=".")
 :marked
   We need two things to launch the application:
+
   1. Angular's browser `bootstrap` function
   1. The application root component that we just wrote.
   
   We import both. Then we call `bootstrap`, passing in the **root component type**, 
   `AppComponent`.
- 
+
+  The `<reference>` tag tells TypeScript how to find the typings for browser shims used by Angular.
+
 .l-sub-section
   :marked
     Learn why we import `bootstrap` from `angular2/platform/browser`