feat: add new demo page to test ISR returning notFound

Author: orinokai

demos/default/pages/getStaticProps/with-revalidate-404.js

@@ -0,0 +1,35 @@
+import Link from 'next/link'
+
+const Show = ({ show }) => (
+  <div>
+    <p>
+      This page uses getStaticProps() to pre-fetch a TV show, but will return a 404 if the current time ends in 0-4.
+    </p>
+
+    <hr />
+
+    <h1>Show #{show.id}</h1>
+    <p>{show.name}</p>
+
+    <hr />
+
+    <Link href="/">
+      <a>Go back home</a>
+    </Link>
+  </div>
+)
+
+export async function getStaticProps(context) {
+  const res = await fetch(`https://api.tvmaze.com/shows/71`)
+  const data = await res.json()
+
+  return {
+    props: {
+      show: data,
+    },
+    notFound: new Date().getMinutes() % 10 < 5,
+    revalidate: 60,
+  }
+}
+
+export default Show