Add example for multi page image labeling (released in 1.15.0)

**Is your feature request related to a problem? Please describe.**
In Label Studio 1.15.0 you added a great feature for multi page image labeling.

I can't get this to work, following the documentation provided on the template page: https://labelstud.io/templates/multi-page-document-annotation. Whatever I try, no images are displayed, nor the controls to go to the next/previous image. No javascript errors are displayed in the console. I have no clue what I do wrong.

Even a barebone `` with the minimal required data is not doing anything:
```json:
task: {
annotations: annotations,
predictions: [],
id: 1,
data: {
images: [
"https://htx-pub.s3.amazonaws.com/demo/images/demo_stock_purchase_agreement/0001.jpg"
]
}
}
```

**Describe the solution you'd like**
For other templates you provide "Preview" and "Open in Playground" links (see example below).

It would be very helpful to add an example for this feature too, so I can double check what I did wrong.