Updated README in src/config/README.md (#57)

Closes #56

Author: sthzg

src/config/README.md

@@ -1,16 +1,34 @@
 # About this folder
+
 This folder holds configuration files for different environments.
 You can use it to provide your app with different settings based on the 
 current environment, e.g. to configure different API base urls depending on 
 whether your setup runs in dev mode or is built for distribution.
 You can include the configuration into your code like this:
 
+**ES2015 Modules**
+
+```js
+import config from 'config';
+```
+
+**Common JS**
+
+Due to Babel6 we need to append `.default`.
+
+```js
+let config = require('config').default;
+```
+
+**Example**
+
 ```javascript
-let react = require('react/addons');
-let config = require('config');
+import React from 'react';
+import config from 'config';
+
 class MyComponent extends React.Component {
-  constructor(props) {
-    super(props);
+  constructor(props, ctx) {
+    super(props, ctx);
     let currentAppEnv = config.appEnv;
   }
 }