Add missing .prototype property entries for DisposableStack/AsyncDisposableStack

[rbuckton]

This adds entries that were missing that are necessary to describe the behavior of the .prototype property on the DisposableStack and AsyncDisposableStack constructors.

cc: @tc39/ecma262-editors

[github-actions]

A preview of this PR can be found at https://tc39.es/proposal-explicit-resource-management/pr/167.

[rbuckton]

Quick clarification: Would this be considered an editorial change since there was no obvious intention to explicitly exclude prototype here, or a needs consensus PR? Im happy to hold off on merging if this needs consensus, even if only perfunctorily.

[ljharb]

Seems like it's normative, but an obvious oversight - so i'd say you can either wait til plenary, or, just merge it and simply notify plenary (obv with the ability to revert it if there were pushback)

[rbuckton]

This was approved by consensus at the July, 2023 TC39 Plenary, but still needs reviews from the editors and reviewers before I can merge.

@waldemarhorwat, @syg, @michaelficarra, @bakkot: can you please review?