demo蓝牙部分wx.writeBLECharacteristicValue的参数serviceId错误

demo的源代码：
`
wx.writeBLECharacteristicValue({
      deviceId: this._deviceId,
      serviceId: this._deviceId,
      characteristicId: this._characteristicId,
      value: buffer,
    })
`
应该改为：
`
wx.writeBLECharacteristicValue({
      deviceId: this._deviceId,
      serviceId: this._serviceId,
      characteristicId: this._characteristicId,
      value: buffer,
    })
`