Add 404 page

src/Error404.js

@@ -0,0 +1,29 @@
+import React from 'react';
+import NavBar from './NavBar';
+import Footer from "./Footer";
+import { HomeRounded as HomeRoundedIcon } from "@material-ui/icons";
+import LinkButton from "./LinkButton";
+
+export default function PageNotFound() {
+	const navbarItems = [
+		{
+			type: "link",
+			link: "/",
+			icon: <HomeRoundedIcon />,
+			hideTextMobile: true,
+		}
+	];
+
+	document.title = "Error 404 | Parandum";
+
+	return (
+		<div>
+			<NavBar items={navbarItems}/>
+			<main>
+				<h1>Error 404</h1>
+				<h3>Sorry, but we can't find that page.</h3>
+			</main>
+			<Footer />
+		</div>
+	)
+}