fix: site-map generating

Author: SekulDev

package.json

@@ -20,6 +20,7 @@
     "homepage": "https://github.com/shuding/nextra-docs-template#readme",
     "dependencies": {
         "next": "^13.0.6",
+        "next-sitemap": "^4.2.3",
         "nextra": "latest",
         "nextra-theme-docs": "latest",
         "react": "^18.2.0",