Add data fetching doc to TOC

Author: gaearon

README.md

@@ -127,6 +127,7 @@ The [User Guide](https://github.com/facebookincubator/create-react-app/blob/mast
 - [Adding a Router](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#adding-a-router)
 - [Adding Custom Environment Variables](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#adding-custom-environment-variables)
 - [Can I Use Decorators?](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#can-i-use-decorators)
+- [Fetching Data with AJAX Requests](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#fetching-data-with-ajax-requests)
 - [Integrating with an API Backend](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#integrating-with-an-api-backend)
 - [Proxying API Requests in Development](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#proxying-api-requests-in-development)
 - [Using HTTPS in Development](https://github.com/facebookincubator/create-react-app/blob/master/packages/react-scripts/template/README.md#using-https-in-development)