Adapt README

Author: Robin Oster

README.md

@@ -36,6 +36,12 @@ translator.translate(params: params) { (result) in
 }
 ```
 
+## Requirements
+
+- iOS 9.0+ / macOS 10.11+ / tvOS 9.0+ / watchOS 2.0+
+- Xcode 8.0+
+- Swift 3.0+
+
 ## License
 
 ```