docs: experimental flag for `watch` caching #4011

Job	Run time
Find path changes	4s
Turborepo Integration (ubuntu-latest)	7m 28s
Rust lints	1m 43s
Turborepo Integration (macos-13)	22m 2s
Turborepo rust check	1m 28s
Turborepo Integration (windows-latest)	24m 55s
Turborepo Rust testing on ubuntu	1m 57s
Turborepo Rust testing on macos	13m 13s
`kitchen-sink` example	0s
`basic` example	0s
Turborepo Rust testing on windows	13m 11s
`non-monorepo` example	0s
`with-tailwind` example	0s
`with-svelte` example	0s
Turborepo Test Summary	1s
Cleanup / cleanup	2s
	1h 26m 4s

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