update zh-cn/application-dev/database/database-storage-guidelines.md.

Signed-off-by: N@ge-yafang <geyafang@huawei.com>
Signed-off-by: N葛亚芳 <geyafang@huawei.com>

zh-cn/application-dev/database/database-storage-guidelines.md

@@ -88,9 +88,9 @@
    context.getFilesDir().then((filePath) => {
        path = filePath;
        console.info("======================>getFilesDirPromsie====================>");
+       
+       let promise = dataStorage.getStorage(path + '/mystore');
    });
-
-   let promise = dataStorage.getStorage(path + '/mystore');
    ```
 
 3. 存入数据。