Removed outdated steps in README about running about setup.py (#3014) #2768

Job	Run time
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	14m 19s
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	49m 31s
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	19m 7s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	25m 15s
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	18m 43s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	15m 25s
pytorch_tutorial_build_worker (7, 15, linux.4xlarge.nvidia.gpu)	17m 50s
pytorch_tutorial_build_worker (8, 15, linux.4xlarge.nvidia.gpu)	18m 35s
pytorch_tutorial_build_worker (9, 15, linux.4xlarge.nvidia.gpu)	32m 36s
pytorch_tutorial_build_worker (10, 15, linux.4xlarge.nvidia.gpu)	23m 3s
pytorch_tutorial_build_worker (11, 15, linux.4xlarge.nvidia.gpu)	38m 19s
pytorch_tutorial_build_worker (12, 15, linux.4xlarge.nvidia.gpu)	17m 56s
pytorch_tutorial_build_worker (13, 15, linux.4xlarge.nvidia.gpu)	18m 5s
pytorch_tutorial_build_worker (14, 15, linux.4xlarge.nvidia.gpu)	11m 35s
pytorch_tutorial_build_worker (15, 15, linux.4xlarge.nvidia.gpu)	18m 49s
pytorch_tutorial_build_manager	18m 51s
	5h 57m 59s

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