Update README.md

Author: bernabe9

README.md

@@ -124,6 +124,22 @@ Returns the current user if exists
 ### deleteUser : Promise
 Deletes the current user from the storage/cookies
 
+## Immutable JS
+Usage of `redux-react-session` with an immutable store is really simple.
+Instead of the `sessionReducer` import the `sessionImmutableReducer`, as the following example:
+
+- Add the session reducer:
+```javascript
+import { combineReducers } from 'redux';
+import { sessionImmutableReducer as session } from 'redux-react-session';
+
+const reducers = {
+  // ... your other reducers here ...
+  session
+};
+const reducer = combineReducers(reducers);
+```
+
 ## Server Rendering
 `redux-react-session` also provides methods to keep the session with server rendering using cookies. So the session will work on the server side as well as the client side.