Updated torchrun instructions #3397

Job	Run time
run-tests (latest, test_prod)	1m 1s
run-tests (latest, test_core)	1m 49s
run-tests (latest, test_cli)	2m 31s
run-tests (latest, test_big_modeling)	1m 14s
run-tests (latest, test_deepspeed)	1m 41s
run-tests (latest, test_fsdp)	1m 21s
run-tests (latest, test_example_differences)	1m 16s
run-tests (latest, test_checkpoint_step)	4m 31s
run-tests (latest, test_checkpoint_epoch)	3m 8s
run-tests (latest, test_rest)	10m 35s
run-tests (minimum, test_prod)	1m 12s
run-tests (minimum, test_core)	1m 53s
run-tests (minimum, test_cli)	2m 29s
run-tests (minimum, test_big_modeling)	1m 27s
run-tests (minimum, test_deepspeed)	1m 17s
run-tests (minimum, test_fsdp)	1m 37s
run-tests (minimum, test_example_differences)	1m 21s
run-tests (minimum, test_checkpoint_step)	3m 15s
run-tests (minimum, test_checkpoint_epoch)	3m 4s
run-tests (minimum, test_rest)	26m 40s
	1h 13m 22s

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