minor fix

Co-authored-by: Miyoung <[email protected]>

training/distributed_training/pytorch/model_parallel/gpt2/smp-train-gpt-simple-sharded-data-parallel.ipynb

@@ -724,7 +724,7 @@
     }
    },
    "source": [
-    "Finally, run the estimator to launch the SageMaker training job of GPT2 model with sharded data parallelism."
+    "Finally, run the `estimator.fit` method to launch the SageMaker training job of the GPT-2 model with sharded data parallelism."
    ]
   },
   {