Update ddp_series_multigpu.rst (#2207)

Author: subramen

beginner_source/ddp_series_multigpu.rst

@@ -177,8 +177,8 @@ Running the distributed training job
    +  ddp_setup(rank, world_size)
       dataset, model, optimizer = load_train_objs()
       train_data = prepare_dataloader(dataset, batch_size=32)
-   -  trainer = Trainer(model, dataset, optimizer, device, save_every)
-   +  trainer = Trainer(model, dataset, optimizer, rank, save_every)
+   -  trainer = Trainer(model, train_data, optimizer, device, save_every)
+   +  trainer = Trainer(model, train_data, optimizer, rank, save_every)
       trainer.train(total_epochs)
    +  destroy_process_group()