shareToStory method expects the widgetLink field in snack_case

shareToStory method expects the widgetLink field in snack_case. But you send params with field widgetLink. 

```
useWebAppShare().shareToStory('url-to.png', {
  // widgetLink: {} // NOW
  // widget_link: {} // MUST BE
})
```

May i contribute first time in my life?)