Complete "Layout Routes".

src/app/(sidebar)/page.tsx

@@ -0,0 +1,15 @@
+import React from "react";
+
+export default function Home() {
+  return (
+    <p id="index-page">
+      This is a demo for React Router.
+      <br/>
+      Check out{" "}
+      <a href="https://reactrouter.com">
+        the docs at reactrouter.com
+      </a>
+      .
+    </p>
+  );
+}