Add ducna.is-a.dev subdomain

domains/d/ducna.json

@@ -0,0 +1,9 @@
+{
+  "owner": {
+    "username": "ducna",
+    "email": "ducna01120@gmail.com"
+  },
+  "record": {
+    "CNAME": "nguyenanhduc.github.io"
+  }
+}