Fix a broken link in rpc_tutorial.rst (#3237) #3744

Job	Run time
pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	14m 20s
pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	51m 35s
pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	20m 39s
pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	30m 38s
pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	21m 53s
pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	19m 21s
pytorch_tutorial_build_worker (7, 15, linux.4xlarge.nvidia.gpu)	21m 56s
pytorch_tutorial_build_worker (8, 15, linux.4xlarge.nvidia.gpu)	15m 55s
pytorch_tutorial_build_worker (9, 15, linux.4xlarge.nvidia.gpu)	22m 11s
pytorch_tutorial_build_worker (10, 15, linux.4xlarge.nvidia.gpu)	17m 38s
pytorch_tutorial_build_worker (11, 15, linux.4xlarge.nvidia.gpu)	17m 32s
pytorch_tutorial_build_worker (12, 15, linux.4xlarge.nvidia.gpu)	28m 57s
pytorch_tutorial_build_worker (13, 15, linux.4xlarge.nvidia.gpu)	40m 29s
pytorch_tutorial_build_worker (14, 15, linux.4xlarge.nvidia.gpu)	40m 16s
pytorch_tutorial_build_worker (15, 15, linux.4xlarge.nvidia.gpu)	28m 55s
pytorch_tutorial_build_manager	21m 21s
	6h 53m 36s

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