[Bundling]Create an example about how to configure hmr (hot module reloading)

[brauliodiez]

More info:

https://webpack.js.org/concepts/hot-module-replacement/

https://webpack.js.org/guides/hot-module-replacement/

React HMR

https://github.com/gaearon/react-hot-loader