feat(iroh): allow to disable docs engine completely (#2390) #8703

Job	Run time
Cross Build Only (armv7-linux-androideabi)	1m 3s
Build wasm32	28s
Cross Build Only (aarch64-linux-android)	1m 3s
Cross Test (i686-unknown-linux-gnu)	3m 37s
Cross Build Only (x86_64-unknown-freebsd)	1m 7s
Cross Build Only (x86_64-unknown-netbsd)	1m 10s
cargo deny	28s
Checking docs	1m 9s
Checking fmt	16s
check_semver	4m 44s
clippy_check	2m 34s
Minimal Supported Rust Version	1m 18s
Run network simulations/benchmarks	7m 9s
CI Test Suite / Tests (ubuntu-latest, stable, all)	2m 43s
CI Test Suite / Tests (ubuntu-latest, stable, none)	3m 20s
CI Test Suite / Tests (ubuntu-latest, stable, default)	2m 10s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	3m 58s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	3m 12s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	4m 5s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	2m 55s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	3m 49s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	2m 54s
	55m 12s

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