Add Vercel verification for tuna.is-a.dev

domains/_vercel.tuna.json

@@ -0,0 +1,9 @@
+{
+  "owner": {
+    "username": "tuanha1508",
+    "email": "tuanafk2006@gmail.com"
+  },
+  "records": {
+    "TXT": "vc-domain-verify=tuna.is-a.dev,fbe88e331fd21183f05a"
+  }
+}