documentation

Pull request #2647: Feature/ZBX-26121 7.0 D

Merge in WEB/documentation from feature/ZBX-26121-7.0-D to release/7.0

* commit '49367fc90942dfc7ecfe9eb34c073516be94b28f':
  ZBX-26121 improved what's new entry, added a correct query_time value.
  ZBX-26121 updated JSON examples, added what's new page and an entry for improved query time precision.