[Navigation Material] Remove usages of undefined Destinations.Home string from code samples in documentation

[ghost]

In the documentation for Navigation Material, the following code sample is present:

@Composable
fun MyApp() {
    val bottomSheetNavigator = rememberBottomSheetNavigator()
    val navController = rememberNavController(bottomSheetNavigator)
    ModalBottomSheetLayout(bottomSheetNavigator) {
        NavHost(navController, Destinations.Home) {
           composable(route = "home") {
               ...
           }
           bottomSheet(route = "sheet") {
               Text("This is a cool bottom sheet!")
           }
        }
    }
}

In the sixth line, Destinations.Home is used, but no such thing is defined anywhere in the documentation, making the code sample somewhat unclear. This pull request replaces NavHost(navController, Destinations.Home) with NavHost(navController, "home") to ensure that the code samples in the Navigation Material documentation donʼt include references to any undefined items. This is consistent with the documentation for the Navigation Animation library.