documentation

Pull request #3211: ZBX-23244 added an example.

Merge in WEB/documentation from feature/ZBX-23224-7.0-D to release/7.0

* commit '0d5538cd899224bbd163691c211826e9ac144539':
  ZBX-23224 added a link.
  ZBX-23224 added a note, fixed example expression.
  ZBX-23244 added an example.