Fix CNAME: Update to correct GitHub Pages URL

Changed CNAME from 'rishukumar.github.io' to 'rishukumark19.github.io' to match the actual GitHub Pages repository URL. The previous URL was not accessible.

domains/rishukumar.json

@@ -5,6 +5,6 @@
     "email": "rishukumar.spam@gmail.com"
   },
   "records": {
-    "CNAME": "rishukumar.github.io"
+    "CNAME": "rishukumark19.github.io"
   }
 }