更新columnsplit示例

Signed-off-by: Nlijuan <lijuan124@huawei.com>

zh-cn/application-dev/reference/arkui-ts/ts-container-columnsplit.md

@@ -47,6 +47,7 @@ struct ColumnSplitExample {
         Text('4').width('100%').height(50).backgroundColor(0xD2B48C).textAlign(TextAlign.Center)
         Text('5').width('100%').height(50).backgroundColor(0xF5DEB3).textAlign(TextAlign.Center)
       }
+      .borderWidth(1)
       .resizeable(true) // 可拖动
       .width('90%').height('60%')
     }.width('100%')
@@ -54,4 +55,4 @@ struct ColumnSplitExample {
 }
 ```
 
-![zh-cn_image_0000001219982707](figures/zh-cn_image_0000001219982707.gif)
+![zh-cn_image_0000001219982708](figures/zh-cn_image_0000001219982708.gif)