Updated torchrun instructions #3410

Job	Run time
run-tests (latest, test_prod)	4m 4s
run-tests (latest, test_core)	6m 8s
run-tests (latest, test_cli)	8m 7s
run-tests (latest, test_big_modeling)	5m 29s
run-tests (latest, test_deepspeed)	5m 59s
run-tests (latest, test_fsdp)	5m 23s
run-tests (latest, test_example_differences)	6m 8s
run-tests (latest, test_checkpoint_step)	7m 44s
run-tests (latest, test_checkpoint_epoch)	7m 0s
run-tests (latest, test_rest)	17m 38s
run-tests (minimum, test_prod)	4m 31s
run-tests (minimum, test_core)	6m 20s
run-tests (minimum, test_cli)	7m 27s
run-tests (minimum, test_big_modeling)	4m 3s
run-tests (minimum, test_deepspeed)	5m 25s
run-tests (minimum, test_fsdp)	6m 7s
run-tests (minimum, test_example_differences)	5m 15s
run-tests (minimum, test_checkpoint_step)	7m 32s
run-tests (minimum, test_checkpoint_epoch)	7m 36s
run-tests (minimum, test_rest)	11m 29s
	2h 19m 25s

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