Adds Swift version support clarification

kzaher · kzaher · commit c57454ce0538 · 2017-09-20T11:47:01.000+02:00
diff --git a/README.md b/README.md
@@ -3,6 +3,9 @@
 
 [![Travis CI](https://travis-ci.org/ReactiveX/RxSwift.svg?branch=master)](https://travis-ci.org/ReactiveX/RxSwift) ![platforms](https://img.shields.io/badge/platforms-iOS%20%7C%20macOS%20%7C%20tvOS%20%7C%20watchOS%20%7C%20Linux-333333.svg) ![pod](https://img.shields.io/cocoapods/v/RxSwift.svg) [![Carthage compatible](https://img.shields.io/badge/Carthage-compatible-4BC51D.svg?style=flat)](https://github.com/Carthage/Carthage) [![Swift Package Manager compatible](https://img.shields.io/badge/Swift%20Package%20Manager-compatible-brightgreen.svg)](https://github.com/apple/swift-package-manager)
 
+* RxSwift 4.x / Swift 4.x can be found in [**rxswift4.0-swift4.0** branch](https://github.com/ReactiveX/RxSwift/tree/rxswift4.0-swift4.0).
+* RxSwift 3.x / Swift 3.x can be found in [**master** branch](https://github.com/ReactiveX/RxSwift/tree/master).
+
 Rx is a [generic abstraction of computation](https://youtu.be/looJcaeboBY) expressed through `Observable<Element>` interface.
 
 This is a Swift version of [Rx](https://github.com/Reactive-Extensions/Rx.NET).
