docs(core): replace angular2/angular2 with the right barrel import.

Related to #5710
Closes #5847

modules/angular2/src/http/base_request_options.ts

@@ -117,7 +117,8 @@ export class RequestOptions {
  * ### Example ([live demo](http://plnkr.co/edit/LEKVSx?p=preview))
  *
  * ```typescript
- * import {provide, bootstrap} from 'angular2/angular2';
+ * import {provide} from 'angular2/core';
+ * import {bootstrap} from 'angular2/platform/browser';
  * import {HTTP_PROVIDERS, Http, BaseRequestOptions, RequestOptions} from 'angular2/http';
  * import {App} from './myapp';
  *

modules/angular2/src/http/base_response_options.ts

@@ -115,7 +115,8 @@ export class ResponseOptions {
  * ### Example ([live demo](http://plnkr.co/edit/qv8DLT?p=preview))
  *
  * ```typescript
- * import {provide, bootstrap} from 'angular2/angular2';
+ * import {provide} from 'angular2/core';
+ * import {bootstrap} from 'angular2/platform/browser';
  * import {HTTP_PROVIDERS, Headers, Http, BaseResponseOptions, ResponseOptions} from
  * 'angular2/http';
  * import {App} from './myapp';

modules/angular2/src/http/index.ts

@@ -2,7 +2,7 @@
 // require('reflect-metadata');
 // require('es6-shim');
 // import {HTTP_PROVIDERS, JSONP_PROVIDERS, Http, Jsonp} from './http';
-// import {Injector} from 'angular2/angular2';
+// import {Injector} from 'angular2/core';
 // export * from './http';
 
 // /**

modules/angular2/src/http/static_request.ts

@@ -25,7 +25,7 @@ import {
  * where it may be useful to generate a `Request` with arbitrary headers and search params.
  *
  * ```typescript
- * import {Injectable, Injector} from 'angular2/angular2';
+ * import {Injectable, Injector} from 'angular2/core';
  * import {HTTP_PROVIDERS, Http, Request, RequestMethod} from 'angular2/http';
  *
  * @Injectable()