Removed outdated steps in README about running about setup.py #2767

Job	Run time
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	14m 44s
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	51m 16s
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	17m 57s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	27m 26s
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	18m 24s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	16m 47s
pytorch_tutorial_build_worker (7, 15, linux.4xlarge.nvidia.gpu)	20m 6s
pytorch_tutorial_build_worker (8, 15, linux.4xlarge.nvidia.gpu)	20m 13s
pytorch_tutorial_build_worker (9, 15, linux.4xlarge.nvidia.gpu)	31m 10s
pytorch_tutorial_build_worker (10, 15, linux.4xlarge.nvidia.gpu)	23m 35s
pytorch_tutorial_build_worker (11, 15, linux.4xlarge.nvidia.gpu)	47m 21s
pytorch_tutorial_build_worker (12, 15, linux.4xlarge.nvidia.gpu)	20m 0s
pytorch_tutorial_build_worker (13, 15, linux.4xlarge.nvidia.gpu)	23m 9s
pytorch_tutorial_build_worker (14, 15, linux.4xlarge.nvidia.gpu)	15m 34s
pytorch_tutorial_build_worker (15, 15, linux.4xlarge.nvidia.gpu)	21m 12s
pytorch_tutorial_build_manager	18m 26s
	6h 27m 20s

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