doc: fix HTTP res 'finish' description
In addition to #21047, after #20611 close event will be emitted on response object after finish.
Checklist
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documentation is changed or added -
commit message follows commit guidelines
Do not update/delete: Banner broadcast message test data
Do not update/delete: Notification broadcast message test data
In addition to #21047, after #20611 close event will be emitted on response object after finish.