Unless I'm missing something, it doesn't look like there is support for the `advertisingSettings` ([ref](https://developer.apple.com/library/content/documentation/General/Conceptual/Apple_News_Format_Ref/AdvertisingSettings.html#//apple_ref/doc/uid/TP40015408-CH93-SW1)) Document property. I imagine it could be added just like `metadata` is implemented. This is a feature request to add support for it.
