🔍️ Add robots.txt and a sitemap

Author: rdwz

package.json

@@ -31,6 +31,8 @@
   },
   "devDependencies": {
     "@astrojs/mdx": "^0.17.2",
+    "@astrojs/sitemap": "^1.1.0",
+    "astro-robots-txt": "^0.4.0",
     "html-escaper": "^3.0.3",
     "postcss": "^8.4.21",
     "postcss-html": "^1.5.0",