Update distributed_checkpoint_recipe.rst (#2590)

Fix formatting to show the last code-block

Author: Svetlana Karslioglu

recipes_source/distributed_checkpoint_recipe.rst

@@ -230,6 +230,7 @@ By default, DCP saves and loads a distributed ``state_dict`` in Single Program M
   Distributed checkpoint support for Multi-Program Multi-Data is still under development.
 
 .. code-block:: python
+
     import os
 
     import torch