Add import statement from various PRs

lessons/09-index-links/README.md

@@ -26,6 +26,10 @@ index route is rendered.
 First lets use the `IndexLink`
 
 ```js
+// App.js
+import { IndexLink, Link } from 'react-router'
+
+// ...
 <li><IndexLink to="/" activeClassName="active">Home</IndexLink></li>
 ```