Docs: Faulty sample code in the documentation of SwipeDelegate QML Type

Please take a look at the example code visible here https://doc.qt.io/qt-6/qml-qtquick-controls2-swipedelegate.html

1. Try to build the app with an example above
2. Try to remove items using swipe

Actual: only item with index 0 is removed

Expected: all items can be removed. Line 
required property int index'
should be moved to the SwipeDelegate scope.