feat: add vercel.json

Author: Chasen-Zhang

vercel.json

@@ -0,0 +1,22 @@
+{
+  "headers": [
+    {
+      "source": "/404",
+      "headers": [
+        {
+          "key": "X-Robots-Tag",
+          "value": "none"
+        }
+      ]
+    },
+    {
+      "source": "/(.*)",
+      "headers": [
+        {
+          "key": "X-Robots-Tag",
+          "value": "index, follow"
+        }
+      ]
+    }
+  ]
+}