Documentation: await all unsettled promises after Context.Run

How do I await all unsettled promises after `Context.Run()`? 

*js code*
```js
(async () => {
  await Promise.resolve();
  throw new Error('test');
})();

console.log('after');
```

*cs code*
```cs
var ctx = new Context();
ctx.Eval("<js code>");
// ctx.WaitForPromises() -> should throw on unhandled rejections
```