[formrecognizer] Update changelog for release#20963

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catalinaperalta merged 2 commits intoAzure:mainfrom catalinaperalta:frv3/updateChangelog

Oct 1, 2021

+3-5

Commits on Sep 30, 2021

update changelog for release
catalinaperalta
committed

Commits on Oct 1, 2021

include snippet about new clients
catalinaperalta
committed