make the redirect permanent to make linkinator happy

apps/documentation/app/page.tsx

@@ -4,5 +4,5 @@ export default function RootPage() {
 	// Redirect to en for now. This is a limitation of static site generation
 	// that we need to work around by creating a client component to read the
 	// navigator.language and redirect to the appropriate locale.
-	redirect("/en");
+	redirect("/en", { permanent: true });
 }