Simplify `lib.rs` doc example (#1330) #4532

Job	Run time
Build	1m 29s
Check mininum supported Rust version	22s
Formatting	16s
Audit	10s
Test (ubuntu-latest)	1m 52s
Test (windows-latest)	3m 32s
Test (Address Sanitizer)	2m 34s
Test (macos-latest)	1m 32s
Clippy	54s
Documentation	25s
Fuzz (translate)	3m 33s
Miri (spec)	6m 42s
Fuzz (execute)	3m 36s
Miri	7m 11s
uDeps	50s
Fuzz (differential)	3m 48s
Coverage	4m 0s
	42m 46s

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