docs($routeProvider): document route.resolve rejection

Add documentation that the $routeChangeError event is fired when a
route resolve promise is rejected

Closes angular#4447

Author: Josh Schumacher

src/ngRoute/route.js

@@ -89,9 +89,12 @@ function $RouteProvider(){
    *        `$location.path()` by applying the current route
    *
    *    - `resolve` - `{Object.<string, function>=}` - An optional map of dependencies which should
-   *      be injected into the controller. If any of these dependencies are promises, they will be
-   *      resolved and converted to a value before the controller is instantiated and the
-   *      `$routeChangeSuccess` event is fired. The map object is:
+   *      be injected into the controller. If any of these dependencies are promises, the router will
+   *      wait for them all to be resolved or one to be rejected before the controller is instantiated.
+   *      If all the promises are resolved successfully, the values of the resolved promises are injected 
+   *      and {@link ngRoute.$route#$routeChangeSuccess $routeChangeSuccess} event is fired.
+   *      If any of the promises are rejected the {@link ngRoute.$route#$routeChangeError $routeChangeError}
+   *      event is fired. The map object is:
    *
    *      - `key` – `{string}`: a name of a dependency to be injected into the controller.
    *      - `factory` - `{string|function}`: If `string` then it is an alias for a service.