Readme/Guide need update for JSZip 3.0

this is not jszip-utils error
just need update guide
i am following the readme and get error

https://github.com/Stuk/jszip-utils/blame/master/documentation/api/getbinarycontent.md#L53

```
Uncaught Error: Error: The constructor with parameters has been removed in JSZip 3.0, please check the upgrade guide.
```

