build

docs: mention `git pack-refs` for co-located repos #6881

Job	Run time
build (ubuntu-latest)	8m 46s
cargo-deny (advisories)	31s
cargo-deny (bans licenses sources)	29s
build (macos-13)	6m 2s
build (windows-latest)	10m 54s
build (ubuntu-latest, --all-features)	6m 57s
Check protos	54s
Clippy check	3m 44s
Check that MkDocs can build the docs	34s
Check formatting	16s
	39m 7s

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