docs: add zone change listener

docs/guide/listener.md

@@ -79,4 +79,12 @@ instance.listener.pageModeChange = (payload: PageMode)=>{}
 用法：
 ```javascript
 instance.listener.saved = (payload: IEditorResult)=>{}
+```
+
+## zoneChange
+功能：区域发生改变
+
+用法：
+```javascript
+instance.listener.zoneChange = (payload: EditorZone)=>{}
 ```