Create thien.json

## Requirements
Unless explicitly specified otherwise by a **maintainer** or in the requirement description, your domain must pass **ALL** the
indicated requirements above.
Please note that we reserve the rights not to accept any domain at our own discretion.
- [x] The file is in the 'domains folder and is in the JSON format.
- [x] The file's name is all lowercased and alphanumeric.
- [x] You have completed your website.
- [x] The website is reachable.
- [x] You're not using Vercel.
- [x] The CNAME record doesn't contain 'https:// or /. 
- [x] There is sufficient information at the 'owner' field.

## Website Link/Preview
https://thiennguyen93.github.io

domains/thien.json

@@ -0,0 +1,9 @@
+{
+    "owner": {
+        "username": "thiennguyen93",
+        "email": "hi@thiennguyen.dev"
+    },
+    "record": {
+        "CNAME": "thiennguyen93.github.io"
+    }
+}