Fix #441 #591 - Generate ESM version of main CJS file at build time

readme.md

@@ -473,6 +473,12 @@ http.createServer(function (req, res) {
 console.log('Server running at http://127.0.0.1:1337/');
 ```
 
+## Using ES Modules
+
+```js
+import { UAParser } from 'ua-parser-js';
+```
+
 ## Using TypeScript
 
 ```sh