update zh-cn/application-dev/reference/arkui-ts/ts-components-canvas-canvasgradient.md.

示例效果图，排版有误，文档中无法显示，已修改；
Signed-off-by: 胡金云 hujinyun2010@qq.com
Signed-off-by: N胡金云 <hujinyun2010@qq.com>

zh-cn/application-dev/reference/arkui-ts/ts-components-canvas-canvasgradient.md

@@ -47,11 +47,11 @@ addColorStop(offset: number, color: string): void
       .width('100%')
       .height('100%')
     }}
-```
+  ```
 
 
 
 
-![zh-cn_image_0000001194032516](figures/zh-cn_image_0000001194032516.png)
+  ![zh-cn_image_0000001194032516](figures/zh-cn_image_0000001194032516.png)
 
  
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