docs: fix and add decorator api doc (#28986) [backport for patch branch]

[AndrewKushnir]

Backport of the "docs: fix and add decorator api doc" commit from master to patch branch.

PR Close #28986

PR Type

What kind of change does this PR introduce?

• Documentation content changes

Does this PR introduce a breaking change?

• Yes
• No

[googlebot]

So there's good news and bad news.

👍 The good news is that everyone that needs to sign a CLA (the pull request submitter and all commit authors) have done so. Everything is all good there.

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[googlebot]

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(Googler, please make sure the reason for overriding the CLA status is clearly documented in these comments.)

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[AndrewKushnir]

Merged this PR as a backport of the "docs: fix and add decorator api doc" commit from master to patch branch with @jbogarthyde review and approval. Thank you.

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