Add Swift example

README.md

@@ -37,9 +37,15 @@ In the iOS simulator, you can use keyboard shortcuts to activate FLEX. `f` will
 Short version:
 
 ```objc
+// Objective-C
 [[FLEXManager sharedManager] showExplorer];
 ```
 
+```swift
+// Swift
+FLEXManager.shared().showExplorer()
+```
+
 More complete version:
 
 ```objc