update

README.md

 ```
 All the code dealing with UIWidgets (```setState()``` in most case) needs to be in window scope.
 
-This is only needed if the code is in methods
+This is needed if the code is in methods
 not invoked by UIWidgets. For example, if the code is in ```completed``` callback of ```UnityWebRequest```, 
 you need to enclose them with window scope. 
 Please see [HttpRequestSample](./Samples/UIWidgetSample/HttpRequestSample.cs) for detail.

Samples/UIWidgetSample/HttpRequestSample.cs

                     UnityWebRequest www = UnityWebRequest.Get("http://worldclockapi.com/api/json/est/now");
                     var asyncOperation  = www.SendWebRequest();
                     asyncOperation.completed += operation => {
-                        Debug.Log(www.downloadHandler.text);
                         var timeData = JsonUtility.FromJson<TimeData>(www.downloadHandler.text);
                         using(WindowProvider.of(this.widget.gameObjOfUIWidgetsPanel).getScope())
                         {