Add a reference to another sample project

Author: Alexey Naumov

README.md

@@ -14,6 +14,8 @@ The app uses the [restcountries.eu](https://restcountries.eu/) REST API to show
 
 **Check out [mvvm branch](https://github.com/nalexn/clean-architecture-swiftui/tree/mvvm) for the MVVM revision of the same app.**
 
+For the example of handling the **authentication state** in the app, you can refer to my [other tiny project](https://github.com/nalexn/uikit-swiftui) that harnesses the locks and keys principle for solving this problem.
+
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