Add Vercel configuration for domain verification

_vercel.tanh1c.json

@@ -0,0 +1,8 @@
+{
+  "owner": {
+    "username": "tanh1c"
+  },
+  "records": {
+    "TXT": "vc-domain-verify=tanh1c.is-a.dev,358548962b9246d56a05"
+  }
+}