Fix docs for Focus.onKey event propagation (#59096)

packages/flutter/lib/src/widgets/focus_scope.dart

@@ -16,7 +16,7 @@ import 'inherited_notifier.dart';
 ///
 /// For keyboard events, [onKey] is called if [FocusNode.hasFocus] is true for
 /// this widget's [focusNode], unless a focused descendant's [onKey] callback
-/// returns false when called.
+/// returns true when called.
 ///
 /// This widget does not provide any visual indication that the focus has
 /// changed. Any desired visual changes should be made when [onFocusChanged] is