docs: add DEPRECATION NOTICE

Author: gajus

README.md

@@ -8,18 +8,15 @@
 
 React CSS Modules implement automatic mapping of CSS modules. Every CSS class is assigned a local-scoped identifier with a global unique name. CSS Modules enable a modular and reusable CSS!
 
-> ⚠️⚠️⚠️
->
-> Note:
+> ## ⚠️⚠️⚠️ DEPRECATION NOTICE ⚠️⚠️⚠️
 >
 > If you are considering to use `react-css-modules`, evaluate if [`babel-plugin-react-css-modules`](https://github.com/gajus/babel-plugin-react-css-modules) covers your use case.
 > `babel-plugin-react-css-modules` is a lightweight alternative of `react-css-modules`.
 >
 > `babel-plugin-react-css-modules` is not a drop-in replacement and does not cover all the use cases of `react-css-modules`.
 > However, it has a lot smaller performance overhead (0-10% vs +50%; see [Performance](https://github.com/gajus/babel-plugin-react-css-modules#performance)) and a lot smaller size footprint (less than 2kb vs +17kb).
 >
-> It is easy to get started!
-> See the demo https://github.com/gajus/babel-plugin-react-css-modules/tree/master/demo
+> It is easy to get started! See the demo https://github.com/gajus/babel-plugin-react-css-modules/tree/master/demo
 
 - [CSS Modules](#css-modules)
     - [webpack `css-loader`](#webpack-css-loader)