Update README with BottomSheet sample (#108)

* Update README with BottomSheet sample

* Update README with BottomSheet sample

Author: jbw0033

README.md

@@ -12,6 +12,7 @@ These are the recipes and what they demonstrate.
 
 ### Layouts and animations
 - **[Dialog](app/src/main/java/com/example/nav3recipes/dialog)**: Shows how to create a Dialog destination.
+- **[BottomSheet](app/src/main/java/com/example/nav3recipes/bottomsheet)**: Shows how to create a BottomSheet destination.
 - **[Custom Scene](app/src/main/java/com/example/nav3recipes/scenes/twopane)**: Shows how to create a custom layout using a `Scene` and `SceneStrategy` (see video of UI behavior below).
 - **[Animations](app/src/main/java/com/example/nav3recipes/animations)**: Override the default animations for all destinations and a single destination.