feat: Add robots.txt for SEO

Author: AugustoL

app/robots.ts

@@ -0,0 +1,11 @@
+import type { MetadataRoute } from "next"
+
+export default function robots(): MetadataRoute.Robots {
+  return {
+    rules: {
+      userAgent: "*",
+      allow: "/",
+    },
+    sitemap: "https://openscan-explorer.github.io/docs/sitemap.xml",
+  }
+}