PRDOC: Document `validate: false` #9564

Job	Run time
preflight / preflight	1m 20s
preflight / ci-versions	1m 3s
test-frame-ui	26m 54s
cargo-check-benches (master)	21m 10s
cargo-check-all-crate-macos	12m 5s
cargo-check-benches (current)	20m 56s
cargo-check-each-crate (1)	15m 43s
cargo-check-each-crate (2)	16m 56s
test-full-crypto-feature	2m 36s
test-node-metrics	8m 10s
cargo-check-each-crate (3)	6m 27s
cargo-check-each-crate (4)	14m 31s
cargo-check-each-crate (5)	21m 20s
cargo-check-each-crate (6)	12m 55s
cargo-check-each-crate (7)	25m 30s
test-frame-examples-compile-to-wasm	2m 52s
check-tracing	2m 16s
test-deterministic-wasm	6m 15s
check-metadata-hash	5m 52s
node-bench-regression-guard	17s
All test misc tests passed	1s
	3h 45m 9s

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