Update compatible version for Swift 4 in README.md (#197)

Author: iwb-kevin-hirsch

README.md

@@ -23,10 +23,10 @@ To install [CocoaPods](http://www.cocoapods.org), run `sudo gem install cocoapod
 
 `DropDown` supports Swift 4.2 since version `2.3.4`.
 
-If you need Swift 4.0, use version 2.3.3:
-- Manually: use tag `2.3.3`
-- CocoaPods: `pod 'DropDown', '~> 2.3.3'`
-- Carthage: `github "AssistoLab/DropDown" ~> 2.3.3`
+If you need Swift 4.0, use version 2.3.2:
+- Manually: use tag `2.3.2`
+- CocoaPods: `pod 'DropDown', '~> 2.3.2'`
+- Carthage: `github "AssistoLab/DropDown" ~> 2.3.2`
 
 ### CocoaPods