Add links to navigation mesh chunks demos

Adds links to navigation mesh chunks demos.

tutorials/navigation/navigation_using_navigationmeshes.rst

@@ -209,6 +209,13 @@ Baking navigation mesh chunks for large worlds
 
    Building and updating individual navigation mesh chunks at runtime.
 
+.. seealso::
+
+    You can see the navigation mesh chunk baking in action in the
+    `Navigation Mesh Chunks 2D <https://github.com/godotengine/godot-demo-projects/tree/master/2d/navigation_mesh_chunks>`__
+    and `Navigation Mesh Chunks 3D <https://github.com/godotengine/godot-demo-projects/tree/master/3d/navigation_mesh_chunks>`__
+    demo projects.
+
 To avoid misaligned edges between different region chunks the navigation meshes have two important properties
 for the navigation mesh baking process. The baking bound and the border size.
 Together they can be used to ensure perfectly aligned edges between region chunks.