documentation

Pull request #3214: ZBX-23244 added an example.

Merge in WEB/documentation from feature/ZBX-23224-7.5-D to release/8.0

* commit '8bd3e97b6d3b0b0e26c511fa8aaa2623b5ddca7c':
  ZBX-23224 added a link.
  ZBX-23224 added a note, fixed example expression.
  ZBX-23244 added an example.