fixed 1824f052 from https://gitee.com/ge-yafang/docs/pulls/3523

update zh-cn/application-dev/reference/apis/js-apis-screenshot.md.
Signed-off-by: N@ge-yafang <geyafang@huawei.com>

zh-cn/application-dev/reference/apis/js-apis-screenshot.md

@@ -5,7 +5,7 @@
 
 ## 导入模块
 
-```
+```js
 import screenshot from '@ohos.screenshot';
 ```
 
@@ -67,7 +67,7 @@ save(options?: ScreenshotOptions, callback: AsyncCallback<image.PixelMap>)
 
 - 示例
 
-  ```
+  ```js
   var ScreenshotOptions = {
   	"screenRect": {
   		"left": 200,
@@ -112,7 +112,7 @@ save(options?: ScreenshotOptions): Promise<image.PixelMap>
 
 - 示例
 
-  ```
+  ```js
   var ScreenshotOptions = {
   	"screenRect": {
   		"left": 200,