Add boilerplate

src/index.js

@@ -0,0 +1,15 @@
+import React from 'react'
+import ReactDOM from 'react-dom'
+import './index.css'
+
+class App extends Component {
+  render() {
+    return (
+      <div className="App">
+        <h1>Hello, React!</h1>
+      </div>
+    )
+  };
+}
+
+ReactDOM.render(<App />, document.getElementById('root'));