Replace example in README to using primitives #4450

Job	Run time
wheel-gpu	14m 44s
wheel-arm64 (macos-latest)	5m 19s
standalone (macos-13)	4m 41s
mpi_standalone (ubuntu-latest)	3m 37s
standalone (ubuntu-latest)	3m 41s
wheel-gpu-cu11	13m 46s
standalone (windows-2019)	3m 19s
wheel (macos-13)	17m 44s
wheel (ubuntu-latest)	32m 5s
wheel (windows-2019)	23m 37s
	2h 2m 33s

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