Use more Reacty example (#705)

Co-authored-by: Diego Augusto <diego.augusto@neemu.com>
Co-authored-by: Richie Bendall <richiebendall@gmail.com>

r/react.js

@@ -1 +1,5 @@
-React.render(<h1>Hello World</h1>, document.body);
+function Hello() {
+  return <h1>Hello World</h1>;
+}
+
+React.render(<Hello />, document.body);