Description of BiometricAccessConstraint[ios/Android] are required for API References #52
Description
https://authgear.github.io/authgear-sdk-xamarin/api/Authgear.Xamarin.BiometricAccessConstraintAndroid.html
https://authgear.github.io/authgear-sdk-xamarin/api/Authgear.Xamarin.BiometricAccessConstraintIos.html
Better add something like:
The 3 settings corresponding to iOS doc at https://developer.apple.com/documentation/security/secaccesscontrolcreateflags/1392879-userpresence, which meant
* Any enrolled fingers, or Face ID
* Only the current enrolled finger, or face ID
* Biometric or passcode.