fix example

Author: SkafteNicki

docs/source-pytorch/data/alternatives.rst

@@ -99,14 +99,19 @@ The webdataset library contains a small wrapper (``WebLoader``) that adds a flui
     import lightning as L
     import webdataset as wds
 
-    dataset = wds.WebDataset(urls)
+    dataset = wds.WebDataset(
+        urls, 
+        # needed for multi-gpu or multi-node training
+        workersplitter=wds.shardlists.split_by_worker,
+        nodesplitter=wds.shardlists.split_by_node,  
+    )
     train_dataloader = wds.WebLoader(dataset)
 
     model = ...
     trainer = L.Trainer()
     trainer.fit(model, train_dataloader)
 
-You can find a complete example `here <https://github.com/webdataset/webdataset-lightning>`__.
+You can find a complete example `here <https://github.com/webdataset/webdataset-lightning>`__. 
 
 NVIDIA DALI
 ^^^^^^^^^^^