docs: update usage docs

README.md

@@ -4,9 +4,19 @@
 
 [![CircleCI](https://circleci.com/gh/electron/universal.svg?style=svg)](https://circleci.com/gh/electron/universal)
 
+## Disclaimer
+
+Work In Progress
+
 ## Usage
 
 
 ```typescript
 import { makeUniversalApp } from '@electron/universal';
+
+await makeUniversalApp({
+  x64AppPath: 'path/to/App_x64.app',
+  arm64AppPath: 'path/to/App_arm64.app',
+  outAppPath: 'path/to/App_universal.app',
+});
 ```