Bump version strings to v0.2.0, update READMEs and benchmarks #39

Job	Run time
test-macos	2m 38s
test-linux	2m 38s
cross-compile (x86_64-linux-gnu)	3m 10s
cross-compile (aarch64-macos-none)	3m 15s
cross-compile (aarch64-linux-gnu)	3m 32s
cross-compile (x86_64-macos-none)	3m 22s
	18m 35s

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