docs(crates/turborepo): add capnp to build dependencies #2264

Job	Run time
Determine jobs to run	18s
Determine jobs to run	18s
Rust lints	5s
Rust lints	1m 33s
Turborepo Integration (ubuntu-latest)	10m 58s
Turborepo Integration (ubuntu-latest)	10m 58s
Turborepo rust check	5s
Turborepo rust check	1m 24s
Turborepo Integration (macos-12)	28m 56s
Turborepo Integration (macos-12)	28m 56s
Turborepo Examples	0s
Turborepo Examples	0s
Turborepo Integration (windows-latest)	29m 8s
Turborepo Integration (windows-latest)	29m 8s
Turborepo Rust testing on ${{ matrix.os.name }}	0s
Turborepo Test Summary	1s
Turborepo Test Summary	1s
Cleanup / cleanup	2s
Cleanup / cleanup	2s
Turborepo Rust testing on ubuntu	2m 33s
Turborepo Rust testing on macos	11m 36s
Turborepo Rust testing on windows	17m 37s
	2h 53m 39s

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