Add Vercel domain verification configuration

domains/_vercel.saminmahmud.json

@@ -0,0 +1,12 @@
+{
+  "owner": {
+    "username": "saminmahmud",
+    "email": "samin.mahmud18@gmail.com"
+  },
+  "records": {
+    "TXT": [
+      "vc-domain-verify=saminmahmud.is-a.dev,a18776d8bc2c5dd99c69",
+      "vc-domain-verify=www.saminmahmud.is-a.dev,880e37821c5ba4777478"
+    ]
+  }
+}