docs: add JSDoc comments to ReadonlySet interface #35698

Job	Run time
knip	33s
typecheck	44s
format	23s
Test Node 24 on ubuntu-latest	8m 22s
Test Node 14 on ubuntu-latest	12m 4s
self-check	51s
Test Node 14 on windows-latest	14m 55s
smoke	55s
baselines	9m 11s
browser-integration	1m 39s
lint	59s
coverage	11m 28s
misc	27s
Test Node 24 on windows-latest	10m 38s
package-size	1m 33s
Test Node lts/* on ubuntu-latest with --no-bundle	10m 54s
required	2s
	1h 25m 38s

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