Update documentation for the default navigation controller.

Source/HotwireConfig.swift

@@ -36,7 +36,7 @@ public struct HotwireConfig {
     }
 
     /// The navigation controller used in `Navigator` for the main and modal stacks.
-    /// Must be a `UINavigationController` or subclass.
+    /// Must be a `HotwireNavigationController` or subclass.
     public var defaultNavigationController: () -> UINavigationController = {
         HotwireNavigationController()
     }