Fixing error in updated example

The new example would throw an error because `Routes` is undefined.

It might be neater to use the new style with React 0.11.x in the examples, not sure how you feel about that. e.g.

var Router = require('router');
React.renderComponent((
  <Router.Routes>

...etc.
Merge pull request #127 from JedWatson/patch-1

Fixing error in updated example