Add FlexAttention examples to SDPA tutorial #46

Job	Run time
build / pytorch_tutorial_build_worker (2, 15, linux.g5.4xlarge.nvidia.gpu)	22m 28s
build / pytorch_tutorial_build_worker (4, 15, linux.g5.4xlarge.nvidia.gpu)	34m 55s
build / pytorch_tutorial_build_worker (3, 15, linux.g5.4xlarge.nvidia.gpu)	26m 1s
build / pytorch_tutorial_build_worker (5, 15, linux.g5.4xlarge.nvidia.gpu)	25m 20s
build / pytorch_tutorial_build_worker (7, 15, linux.g5.4xlarge.nvidia.gpu)	26m 47s
build / pytorch_tutorial_build_worker (1, 15, linux.g5.12xlarge.nvidia.gpu)	17m 8s
build / pytorch_tutorial_build_worker (12, 15, linux.g5.4xlarge.nvidia.gpu)	17m 57s
build / pytorch_tutorial_build_worker (6, 15, linux.g5.4xlarge.nvidia.gpu)	29m 52s
build / pytorch_tutorial_build_worker (11, 15, linux.g5.4xlarge.nvidia.gpu)	29m 16s
build / pytorch_tutorial_build_worker (10, 15, linux.g5.4xlarge.nvidia.gpu)	27m 23s
build / pytorch_tutorial_build_worker (9, 15, linux.g5.4xlarge.nvidia.gpu)	22m 33s
build / pytorch_tutorial_build_worker (14, 15, linux.g5.4xlarge.nvidia.gpu)	17m 15s
build / pytorch_tutorial_build_worker (13, 15, linux.g5.4xlarge.nvidia.gpu)	30m 44s
build / pytorch_tutorial_build_worker (15, 15, linux.g5.4xlarge.nvidia.gpu)	16m 54s
build / pytorch_tutorial_build_worker (8, 15, linux.g5.4xlarge.nvidia.gpu)	22m 59s
build / pytorch_tutorial_build_manager	0s
	6h 7m 32s

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