Added 404 page and robots.txt

pages/404.tsx

@@ -0,0 +1,21 @@
+import Page from "../components/Page";
+import Navbar from "../components/Navbar";
+import Footer from "../components/Footer";
+
+const NotFound = () => (
+  <Page title="Page not found" description="This page either doesn't exist or has been deleted">
+    <Navbar />
+    <div className="message">
+      <div>
+        <div className="header">Not found</div>
+        <div className="subtitle">This page either doesn't exist or has been deleted</div>
+        <a href="/" className="link button">
+          Go back
+        </a>
+      </div>
+    </div>
+    <Footer />
+  </Page>
+);
+
+export default NotFound;

public/robots.txt

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+Disallow /binas