documentation

Pull request #2909: ZBX-25929 removed mentions of time_size, date_size, tzone_size fields, updated screenshots.

Merge in WEB/documentation from feature/ZBX-25929-7.0-D to release/7.0

* commit '638e5fdb874bc7b11416ed8c25dbce2ee498d89b':
  ZBX-25929 updated dashboard screenshots that show more sparkline.
  ZBX-25929 updated screenshots.
  ZBX-25929 moved information to the correct page.
  ZBX-25929 updated a screenshot.
  ZBX-25929 removed mentions of time_size, date_size, tzone_size fields, updated screenshots.