Better wording in compression level docs #384

Job	Run time
Rustfmt & Docs	23s
WebAssembly (wasm32-unknown-unknown)	17s
Minimum Rust compiler (windows-2022)	2m 29s
WebAssembly (wasm32-wasi)	16s
Minimum Rust compiler (macos-latest)	1m 27s
Minimum Rust compiler	48s
Minimum Rust compiler (ubuntu-latest)	1m 15s
Test (stable)	1m 34s
Test (beta)	1m 34s
Test (nightly)	1m 25s
Test (macos)	1m 53s
Test (windows)	5m 42s
Test (mingw)	2m 0s
	21m 3s

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