message: chore(wheel): add selectedIndexChanged event example for wheel
diff: useTransition: false,
  probeType: 3
  })
  + // < v2.1.0
  this.wheel.on('scrollEnd', () => {
  this.$emit(EVENT_CHANGE, this.wheel.getSelectedIndex())
  })
  + // v2.1.0, only when selectedIndex changed
  + this.wheel.on('selectedIndexChanged', (index) => {
  + console.log(index)
  + })
  } else {
  this.wheel.refresh()
  }
  