docs: add LayerMap example (#27388) #1

Job	Run time
compute-hash (aarch64-darwin, macos-latest)	9m 17s
compute-hash (x86_64-darwin, macos-15-intel)	17m 42s
compute-hash (aarch64-linux, blacksmith-4vcpu-ubuntu-2404-arm)	1d 0h 0m 0s
compute-hash (x86_64-linux, blacksmith-4vcpu-ubuntu-2404)	1d 0h 0m 0s
update-hashes	-1s
	2d 0h 26m 58s

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