Update README.md

Author: TikhomirovSergey

README.md

@@ -80,6 +80,7 @@ You can get it on [WIKI](https://github.com/appium/java-client/wiki)
   - `io.appium.java_client.remote.AndroidMobileCapabilityType.ANDROID_INSTALL_TIMEOUT`
   - `io.appium.java_client.remote.AndroidMobileCapabilityType.NATIVE_WEB_SCREENSHOT`
   - `io.appium.java_client.remote.AndroidMobileCapabilityType.ANDROID_SCREENSHOT_PATH`. The pull request: [#452](https://github.com/appium/java-client/pull/452)
+- `org.openqa.selenium.Alert` was reimplemented for iOS. Details: [#459](https://github.com/appium/java-client/pull/459) 
 
 *4.1.1*