Mention indeterminate state for Qt Quick Controls 2 ProgressBar customization

contentItem: Item {
       anchors.fill: parent
       anchors.margins: 1
       visible: control.indeterminate
       clip: true
       Row {
           Repeater {
               Rectangle {
                   color: index % 2 ? "steelblue" : "lightsteelblue"
                   width: 20 ; height: control.height
               }
               model: control.width / 20 + 2
           }
           XAnimator on x {
               from: 0 ; to: -40
               loops: Animation.Infinite
               running: control.indeterminate
           }
       }
   }
}