Update sheetLargestUndimmedDetentIndex doc for keyboard handling (#1465)

Author: t0maboro

versioned_docs/version-7.x/native-stack-navigator.md

@@ -560,6 +560,14 @@ Additionaly there are following options available:
 - `none` - there will be dimming view for all detents levels,
 - `last` - there won't be a dimming view for any detent level.
 
+:::warning
+
+On iOS, the native implementation might resize the the sheet w/o explicitly changing the detent level, e.g. in case of keyboard appearance.
+
+In case after such resize the sheet exceeds height for which in regular scenario a dimming view would be applied - it will be applied, even if the detent has not effectively been changed.
+
+:::
+
 Defaults to `none`, indicating that the dimming view should be always present.
 
 Only supported on Android and iOS.