docs(readme): adding extract css chunks to readme

Adding it to the documentation as a alternative  extended version of mini css extract.
Extract css chunks offers hot module reloading while in development, allowing for good performance on the client and build.
As you guys will know, mini css is fast, this brings the benefits of it to development without losing the ability to hot reload.

Author: ScriptedAlchemy

README.md

@@ -658,7 +658,9 @@ module.exports = {
 ### Extract
 
 For production builds it's recommended to extract the CSS from your bundle being able to use parallel loading of CSS/JS resources later on.
-This can be achieved by using the [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) to extract the CSS when running in production mode.
+- This can be achieved by using the [mini-css-extract-plugin](https://github.com/webpack-contrib/mini-css-extract-plugin) to extract the CSS when running in production mode. 
+
+- As an alternative, if seeking better development performance and css outputs that mimic production. [extract-css-chunks-webpack-plugin](https://github.com/faceyspacey/extract-css-chunks-webpack-plugin) offers a hot module reload friendly, extended version of mini-css-extract-plugin. HMR real CSS files in dev, works like mini-css in non-dev
 
 ## Contributing