documentation

Pull request #2115: feature/ZBXNEXT-8690-7.0-D. filter media type usage in actions.

Merge in WEB/documentation from feature/ZBXNEXT-8690-7.0-D to release/7.0

* commit '55e8d7f17d451734e2a69d5be984b54452c863dd':
  [ZBXNEXT-8690] filter media type usage in actions (specified change version)
  [ZBXNEXT-8690] filter media type usage in actions (updated "Quickstart" section)
  [ZBXNEXT-8690] filter media type usage in actions