Add Vercel TXT verification configuration

domains/_vercel.tx.json

@@ -0,0 +1,9 @@
+{
+    "owner": {
+        "username": "Dr-T",
+        "email": "xandertang@qq.com"
+    },
+    "records": {
+        "TXT": "vc-domain-verify=tx.is-a.dev,75b4b92999bc0a8486ef"
+    }
+}