added flux app guide

Author: ryanflorence

docs/guides/flux.md

@@ -0,0 +1,46 @@
+React Router in a Flux App
+==========================
+
+```js
+///////////////////////////////////////////////////////////
+// router.js
+var routes = require('./routes');
+var Router = require('react-router');
+
+// we can create a router instance before "running" it
+var router = Router.create({
+  routes: routes,
+  location: Router.HistoryLocation
+});
+
+module.exports = router;
+
+///////////////////////////////////////////////////////////
+//SomeActions.js
+
+// and then action creators can require it like other
+// singletons in the app (or if you don't use singletons,
+// do something else with the router you created in
+// router.js)
+var router = require('../router');
+
+module.exports = {
+  doSomeTransitionThing: function () {
+    router.transitionTo('somewhere');
+  }
+};
+
+///////////////////////////////////////////////////////////
+// main.js
+
+// finally, run it in your main script
+var React = require('react');
+var router = require('./router');
+router.run(function (Handler, state) {
+  // you might want to push the state of the router to a
+  // store for whatever reason
+  RouterActions.routeChange({routerState: state});
+  React.render(<Handler/>, document.body);
+});
+```
+