Add decode benches, update README.md #237

Job	Run time
feature checks	43s
docs	25s
Clippy	22s
fmt	14s
Fuzz	46s
Outdated	12s
Miri (x86_64-unknown-linux-gnu, --no-default-features)	1m 19s
Test (x86_64-unknown-linux-gnu, nightly)	32s
Miri (x86_64-unknown-linux-gnu)	1m 22s
Test (x86_64-unknown-linux-gnu, beta)	3m 40s
Miri (x86_64-unknown-linux-gnu, --all-features)	1m 7s
Test (x86_64-unknown-linux-gnu, stable)	28s
Miri (x86_64-unknown-linux-gnu, --features force-generic)	1m 19s
Test (x86_64-unknown-linux-gnu, 1.64)	4m 25s
Test (aarch64-unknown-linux-gnu, nightly)	53s
Test (aarch64-unknown-linux-gnu, beta)	1m 3s
Test (aarch64-unknown-linux-gnu, stable)	3m 30s
Test (aarch64-unknown-linux-gnu, 1.64)	3m 52s
	26m 12s

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