Documentation of `AppNotificationManager.IsSupported` seems to be wrong

[Lightczx]

Describe the bug

The AppNotificationManager docs has a Note about PushNotificationManager which is wrong and should be AppNotificationManager itself.

And the code only checks if the process is elevated. https://github.com/microsoft/WindowsAppSDK/blob/4eb59c31706a73bed565ce3c5e67456511f1c6f5/dev/AppNotifications/AppNotificationManager.cpp#L105-L109

Seems like only PushNotificationManager depends on the singleton package?

Expected behavior

The doc should be correct.

NuGet package version

Windows App SDK 1.5.4: 1.5.240607001