docs: fix index.html.md causing 404 (#12241)

* docs: fix index.html.md causing 404

* update next.js

* test

* test

* test

* test

* fix revalidate

* test

* test

* test

* test

* test

* test

* test

* test

* clean up

www/package.json

@@ -33,7 +33,7 @@
     "@babel/eslint-parser": "^7.25.9",
     "@eslint/js": "9.13.0",
     "@types/eslint__js": "8.42.3",
-    "eslint-config-next": "15.0.4",
+    "eslint-config-next": "15.3.1",
     "eslint-config-prettier": "9.1.0",
     "eslint-config-turbo": "2.2.3",
     "eslint-plugin-markdown": "5.1.0",