documentation

Pull request #3696: Feature/ZBXNEXT-9595 7.5 D

Merge in WEB/documentation from feature/ZBXNEXT-9595-7.5-D to release/8.0

* commit '01f5a0fe895a85db0134312d29c7a847c4237584':
  [ZBXNEXT-9595] minor wording change
  [ZBXNEXT-9595] Entry moved from What's New to Upgrade notes, wording updated
  [ZBXNEXT-9595] updated wording
  [ZBXNEXT-9595] updated What's New page
  [ZBXNEXT-9595] updated Request body type parameter description