docs(router): add api docs

modules/@angular/router/index.ts

@@ -1,7 +1,7 @@
 /**
  * @module
  * @description
- * Alternative implementation of the router. Experimental.
+ * Maps application URLs into application states, to support deep-linking and navigation.
  */
 
 export {Router, RouterOutletMap} from './src/router';
@@ -15,4 +15,24 @@ export {ROUTER_PROVIDERS} from './src/router_providers';
 import {RouterOutlet} from './src/directives/router_outlet';
 import {RouterLink} from './src/directives/router_link';
 
+/**
+ * A list of directives. To use the router directives like {@link RouterOutlet} and
+ * {@link RouterLink}, add this to your `directives` array in the {@link View} decorator of your
+ * component.
+ *
+ * ```
+ * import {Component} from '@angular/core';
+ * import {ROUTER_DIRECTIVES, Routes} from '@angular/router-deprecated';
+ *
+ * @Component({directives: [ROUTER_DIRECTIVES]})
+ * @RouteConfig([
+ *  {...},
+ * ])
+ * class AppCmp {
+ *    // ...
+ * }
+ *
+ * bootstrap(AppCmp);
+ * ```
+ */
 export const ROUTER_DIRECTIVES: any[] = /*@ts2dart_const*/[RouterOutlet, RouterLink];