Update bench/README.md with latest zwasm 5-runtime benchmark comparison #32

Job	Run time
test-linux	1m 10s
cross-compile (aarch64-linux-gnu)	1m 51s
test-macos	1m 19s
cross-compile (x86_64-macos-none)	1m 45s
cross-compile (x86_64-linux-gnu)	13s
cross-compile (aarch64-macos-none)	1m 52s
	8m 10s

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