feat(ad-hoc): update readme (#362)

Example/README.md

@@ -4,7 +4,7 @@ Project demonstrates multiple flows that ProcessOut framework is capable of.
 
 ## Requirements
 
-- A recent version of Xcode (tested with 15.4)
+- A recent version of Xcode (tested with 16.0)
 - [Homebrew](https://brew.sh) package manager
 
 ### Installation

README.md

@@ -24,13 +24,18 @@ Get started with our ProcessOut [documentation](https://docs.processout.com/) or
 > is based on SwiftUI, so styling is not compatible with ProcessOut (that is based on UIKit). Also
 > beware that UI in ProcessOut will be removed in `5.0.0`.
 
+> [!WARNING]
+>
+> Checkout3DS is currently incompatible with Xcode 16, which also affects ProcessOutCheckout3DS. If you
+> depend on this functionality, please use version 4.20.0 with Xcode 15 until the issue is resolved.
+
 ## Contributing
 
 We welcome contributions of any kind including new features, bug fixes, and general improvements.
 
 ### Development requirements
 
-- A recent version of Xcode (tested with 15.4)
+- A recent version of Xcode (tested with 16.0)
 - [Homebrew](https://brew.sh/) package manager
 
 ### Installation