docs(router): alias should be as

Author: matsko

modules/angular2/src/router/router_link.ts

@@ -17,7 +17,7 @@ import {Location} from './location';
 
  * ```
  * @RouteConfig({
- * path: '/user', component: UserCmp, alias: 'user'
+ * path: '/user', component: UserCmp, as: 'user'
  * });
  * class MyComp {}
  * ```