update readme

README.md

@@ -63,7 +63,7 @@ for more details.
 - app_id. Recommend. It'll be used to generate scheme on iOS。This is not used to init WeChat SDK so you still need to call `fluwx.registerApi` manually.
 - debug_logging. Optional. Enable logs by setting it `true`.
 - flutter_activity. Optional. This is usually used by cold boot from WeChat on Android. `Fluwx` will try to launch launcher activity if not set.
-- universal_link. Required for iOS. It'll be used to generate universal link on your projects.
+- universal_link. Recommend for iOS. It'll be used to generate universal link on your projects.
 - scene_delegate. Optional. Use `AppDelegate` or `SceneDelegate`. See [official documents](https://developers.weixin.qq.com/doc/oplatform/Mobile_App/Access_Guide/iOS.html) for more details.
 
 * For iOS

README_CN.md

@@ -64,7 +64,7 @@ dependencies:
 - app_id. 推荐. 它将用于生成iOS的url_scheme。这并不会替你初始化微信SDK，所以你还是自己调用`fluwx.registerApi`。
 - debug_logging. 可选. 把它设置成`true`可以开启日志。
 - flutter_activity. 可选. 这个通常是用于Android的冷启动。如果不设置任何值，`Fluwx`将尝试启动launcher activity.
-- universal_link. iOS 必填. 它将用自动配置universal_link。
+- universal_link. iOS 推荐. 它将用自动配置universal_link。
 - scene_delegate. iOS 可选. 使用 `AppDelegate` 还是使用 `SceneDelegate`. 查阅[官方文档](https://developers.weixin.qq.com/doc/oplatform/Mobile_App/Access_Guide/iOS.html)了解更多.
 
 * For iOS