docs: update readme

Author: uerceg

README.md

@@ -1,6 +1,6 @@
 # Adjust SDK for Flutter
 
-This is the [Adjust](https://adjust.com)™  SDK for iOS. Documentation is available on our [developer docs](https://dev.adjust.com/en/sdk/flutter/?version=v5).
+This is the [Adjust](https://adjust.com)™  SDK for Flutter. Documentation is available on our [developer docs](https://dev.adjust.com/en/sdk/flutter/?version=v5).
 
 ## License