docs:更新会话存档README.md文件内的示例代码 (#527)

work/msgaudit/README.md

@@ -64,13 +64,14 @@ func main() {
 
 		if chatInfo.Type == "image" {
 			image, _ := chatInfo.GetImageMessage()
-			sdkfileid := image.Image.SdkFileID
+			sdkFileID := image.Image.SdkFileID
 
 			isFinish := false
 			buffer := bytes.Buffer{}
+			indexBuf := ""
 			for !isFinish {
 				//获取媒体数据
-				mediaData, err := client.GetMediaData("", sdkfileid, "", "", 5)
+				mediaData, err := client.GetMediaData(indexBuf, sdkFileID, "", "", 5)
 				if err != nil {
 					fmt.Printf("媒体数据拉取失败：%v \n", err)
 					return
@@ -79,6 +80,7 @@ func main() {
 				if mediaData.IsFinish {
 					isFinish = mediaData.IsFinish
 				}
+				indexBuf = mediaData.OutIndexBuf
 			}
 			filePath, _ := os.Getwd()
 			filePath = path.Join(filePath, "test.png")