build

Added docs about installation under Gentoo Linux #13608

Job	Run time
Check protos	27s
Build jj-lib without Git support	44s
build (ubuntu-latest)	4m 29s
Check formatting	15s
build (macos-13)	5m 53s
build (macos-14)	3m 44s
build (windows-latest)	9m 41s
build (ubuntu-latest, --all-features)	5m 26s
cargo-deny (advisories)	23s
cargo-deny (bans licenses sources)	22s
Clippy check	2m 32s
Check that MkDocs can build the docs	21s
Check that MkDocs can build the docs with Poetry 1.8	34s
	34m 51s

Provide feedback