Add sandbox project using Contentful CMS

I used the boilerplate/typescript project as a starting point. This project
fetches and renders books that I'm defining in a Contentful CMS that I created.

website/sandbox/contentful/src/index.tsx

@@ -0,0 +1,12 @@
+import React from "react";
+import ReactDOM from "react-dom";
+import App from "./App";
+import { Provider } from "react-redux";
+import store from "./store";
+
+ReactDOM.render(
+  <Provider store={store}>
+    <App />
+  </Provider>,
+  document.getElementById("mount")
+);