Update deviceMotion.md

docs/api/system/deviceMotion.md

-#### 设备方向
+#### 监听设备方向变化
 
 仅微信小程序平台支持，[规范详情](https://developers.weixin.qq.com/miniprogram/dev/api/device/motion/wx.startDeviceMotionListening.html)
 
+在App平台，也可以通过监听窗体大小变化onResize来实现此类需求。[详见](https://uniapp.dcloud.io/collocation/frame/lifetime?id=%e9%a1%b5%e9%9d%a2%e7%94%9f%e5%91%bd%e5%91%a8%e6%9c%9f)