Update README to require react v16.4 and react-redux v6 or later

README.md

@@ -25,6 +25,8 @@ Main features
 
 Installation
 -----------
+Connected React Router requires **React 16.4 and Redux 6.0 or later**.
+
 Using [npm](https://www.npmjs.com/):
 
     $ npm install --save connected-react-router
@@ -39,7 +41,7 @@ Usage
 
 - Create a `history` object.
 - Create root reducer as a function that takes `history` as an argument and returns reducer.
-- Add `router` reducer into root reducer by passing `history` to `connectRouter`. Note: The key MUST be `router`.
+- Add `router` reducer into root reducer by passing `history` to `connectRouter`. Note: The key **MUST** be `router`.
 - Use `routerMiddleware(history)` if you want to dispatch history actions (e.g. to change URL with `push('/path/to/somewhere')`).