added example user database URI

Author: eishakaushal

electron/models/UserModel.ts

@@ -1,5 +1,5 @@
 // Insert the MongoDB URI for your private User database in place of the example URI provided below.
-const MONGO_URI = 'mongodb+srv://haoyuliu0914:[email protected]/?retryWrites=true&w=majority';
+const MONGO_URI = 'mongodb://username:password@hostname:port/database';
 
 const mongoose = require('mongoose');