Update docs (#670)

docs/content/user-guide/zh/storage/general.md

@@ -73,3 +73,5 @@ CallbackName |	回调的订阅者名称 | string
 * LiteDB ([@maikebing](https://github.com/maikebing)) ：https://github.com/maikebing/CAP.Extensions
 
 * SQLite & Oracle ([@cocosip](https://github.com/cocosip)) ：https://github.com/cocosip/CAP-Extensions   
+
+* SmartSql ([@xiangxiren](https://github.com/xiangxiren)) ：https://github.com/xiangxiren/SmartSql.CAP