Fix a broken link in intro.py (#3430) #4686

Job	Run time
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	21m 38s
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	15m 35s
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	40m 22s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	15m 8s
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	23m 10s
pytorch_tutorial_build_worker (9, 15, linux.g5.4xlarge.nvidia.gpu)	18m 45s
pytorch_tutorial_build_worker (8, 15, linux.g5.4xlarge.nvidia.gpu)	16m 31s
pytorch_tutorial_build_worker (11, 15, linux.g5.4xlarge.nvidia.gpu)	22m 4s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	19m 53s
pytorch_tutorial_build_worker (10, 15, linux.g5.4xlarge.nvidia.gpu)	27m 44s
pytorch_tutorial_build_worker (7, 15, linux.g5.4xlarge.nvidia.gpu)	17m 20s
pytorch_tutorial_build_worker (15, 15, linux.g5.4xlarge.nvidia.gpu)	34m 29s
pytorch_tutorial_build_worker (12, 15, linux.g5.4xlarge.nvidia.gpu)	32m 0s
pytorch_tutorial_build_worker (13, 15, linux.g5.4xlarge.nvidia.gpu)	23m 27s
pytorch_tutorial_build_worker (14, 15, linux.g5.4xlarge.nvidia.gpu)	19m 7s
pytorch_tutorial_build_manager	23m 18s
	6h 10m 31s

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