[examples/data-literate][m]: factor our a working markdown+CSV (data literate) example from site (where we already had a demo).

* removed a few extraneous things
* added the README.md with some instructions

examples/data-literate/pages/_app.js

@@ -0,0 +1,8 @@
+import '../styles/globals.css'
+import '../styles/tailwind.css'
+
+function MyApp({ Component, pageProps }) {
+  return <Component {...pageProps} />
+}
+
+export default MyApp