(docs) update contributing

Author: antoine92190

.github/CONTRIBUTING.md

@@ -9,5 +9,5 @@
 - If you want to test using Firebase, you can follow the steps [here](https://github.com/antoine92190/vue-advanced-chat#using-with-firestore)
 - You can use the code in `demo/src/ChatContainer.vue` or write your own code to test the chat
 - Run `npm run serve` inside the `demo` folder to open the demo app
-- You need to keep `import ChatWindow from './../../src/lib/ChatWindow'` to use the chat code locally and see your modifications live
+- You need to uncomment `import { register } from './../../src/lib/index.js'` to use the chat code locally and see your modifications live
 - When you are done with your changes, you can create a pull request and make sure you filled in the template correctly