add description for framerate adjustment feature

Author: zhuxingwei

README-ZH.md

@@ -202,6 +202,9 @@ UIWidgets也支持Gif！
 #### 七、图片导入设置
 请将图片放入StreamingAssets下，而后用```Image.file```读取
 
+#### 八、自动降低帧率
+目前在默认情况下，为了保证流畅度，项目在各个平台上均会以最高的刷新频率运行。不过您可以通过在代码中设置```SchedulerBinding.MEnableAutoAdjustFramerate = true```的方式来开启自动降帧的功能：该功能开启后，在UI内容不变的情况下我们将降低项目的刷新率来降低耗电。
+
 
 ## 调试UIWidgets应用程序
 

README.md

@@ -213,6 +213,10 @@ want to show the status bar in your App, you can disable```Start in fullscreen``
 #### Image Import Setting
 Please put images under StreamingAssets folder, a and loading it using ```Image.file```.
 
+#### Auto Framerate Adjustment
+You can enable this feature by setting ```SchedulerBinding.MEnableAutoAdjustFramerate = true``` in your project, which will automatically drop the frame rate of your App to 0 if the UI contents of UIWidgetsPanel is not changed for some time. This will help to prevent battery drain on mobile devices significantly. 
+
+Note that this feature is disabled by default though.
 
 ## Debug UIWidgets Application