Update README.md

fixed piotrwitek#52

Author: piotrwitek

README.md

@@ -67,6 +67,8 @@ npm i -D @types/react @types/react-dom @types/react-redux utility-types
 "react-redux" - `@types/react-redux`  
 ["utility-types"](https://github.com/piotrwitek/utility-types) - usefull utility types used throughout the guide  
 
+> *NB: Guide uses redux v4.x.x types. For version v3.x.x please check [this config](https://github.com/piotrwitek/react-redux-typescript-guide/blob/master/playground/tsconfig.json#L5))  
+
 [⇧ back to top](#table-of-contents)
 
 ---