Added doc for nvdec #402

Job	Run time
generate-matrix / generate	4s
Build and Upload wheel / manywheel-py3_9-cuda11_8	6m 49s
Build and Upload wheel / manywheel-py3_9-cuda12_1	6m 54s
Build and Upload wheel / manywheel-py3_9-cuda12_4	7m 15s
Build and Upload wheel / upload / manywheel-py3_9-cuda11_8	13s
Build and Upload wheel / upload / manywheel-py3_9-cuda12_1	17s
Build and Upload wheel / upload / manywheel-py3_9-cuda12_4	13s
install-and-test (3.9, 11.8, 5)	5m 38s
install-and-test (3.9, 11.8, 6)	8m 26s
install-and-test (3.9, 11.8, 7)	8m 28s
install-and-test (3.9, 12.1, 5)	6m 0s
install-and-test (3.9, 12.1, 6)	9m 14s
install-and-test (3.9, 12.1, 7)	9m 4s
install-and-test (3.9, 12.4, 5)	6m 4s
install-and-test (3.9, 12.4, 6)	9m 25s
install-and-test (3.9, 12.4, 7)	9m 20s
	1h 33m 24s

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