Fix: #3833 Feedback about Multi GPU training with DDP (#3838)

Fixes #3833 Feedback about Multi GPU training with DDP

## Description
<!--- Describe your changes in detail -->

At the end of the page, it says "Here's what the code looks like: " but
it does not actually show the full code. The code was not visible
because there was no proper spacing. Have corrected the spacing.


Co-authored-by: sekyondaMeta <127536312+sekyondaMeta@users.noreply.github.com>
Co-authored-by: Svetlana Karslioglu <svekars@meta.com>

Author: 3 people

beginner_source/ddp_series_multigpu.rst

@@ -202,6 +202,7 @@ Running the distributed training job
 Here's what the code looks like:
 
 .. code-block:: python
+
    def main(rank, world_size, total_epochs, save_every):
       ddp_setup(rank, world_size)
       dataset, model, optimizer = load_train_objs()
@@ -218,7 +219,6 @@ Here's what the code looks like:
       mp.spawn(main, args=(world_size, total_epochs, save_every,), nprocs=world_size)
 
 
-
 Further Reading
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