intro-to-extensions not working.

[Tymaku]

Xamarin.iOS 14.20.0.24 + iOS simulator 14.5.
Sweeping screen down shows empty notification's panel.

[Chris Hamons]

Thanks for the report. I could reproduce it not showing up in the list.

Fixed in #417 - the extension now shows up. Though for modern cases you should look towards Widgets over Today extensions:

https://developer.apple.com/documentation/widgetkit/creating-a-widget-extension