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

@@ -122,7 +122,8 @@
        console.info("Failed to get the value of 'startup'. Cause: " + err);
      })
    }).catch((err) => {
-       console.info("Failed to get preferences.")});
+     console.info("Failed to get preferences.")
+   });
    ```
 
 5. 数据持久化。