Updating documentation to demonstrate accurate use of AlertState<Action> handling (pointfreeco#125)

Co-authored-by: Hitesh Savaliya <[email protected]>

Author: hisavali

Sources/SwiftUINavigationCore/AlertState.swift

@@ -36,12 +36,14 @@ import SwiftUI
 /// ```swift
 /// class HomeScreenModel: ObservableObject {
 ///   // ...
-///   func alertButtonTapped(_ action: AlertAction) {
+///   func alertButtonTapped(_ action: AlertAction?) {
 ///     switch action {
 ///     case .delete:
 ///       // ...
 ///     case .removeFromHomeScreen:
 ///       // ...
+///     case .none:
+///       // ...
 ///     }
 ///   }
 /// }