pull_request_review_properties.md

Key	Type	Description
action	string	The action that was performed. Can be one of: submitted - A pull request review is submitted into a non-pending state. edited - The body of a review has been edited. dismissed - A review has been dismissed.
pull_request	object	The pull request the review pertains to.
review	object	The review that was affected.
changes[body][from]	string	The previous version of the body if the action was edited.