documentation

Pull request #1156: feature/ZBXNEXT-297-7.0-D: Remote command execution via active checks.

Merge in WEB/documentation from feature/ZBXNEXT-297-7.0-D to release/7.0

* commit '5affe2a36457f97867a47835f65d5f5212456b1d':
  [ZBXNEXT-297] Remote command execution via active checks supported only since agent 7.0
  [ZBXNEXT-297] Remote command execution via active checks supported only since agent 7.0
  [ZBXNEXT-297] Removed ambiguity from dealing with script timeout
  [ZBXNEXT-297] Updated "command" to "commands", and info on dealing with script timeout
  [ZBXNEXT-297] Removed ambiguity from the "What's new" entry on active remote commands
  [ZBXNEXT-297] Updated formatting
  [ZBXNEXT-297] Remote command execution via active checks
  [ZBXNEXT-297] Remote command execution via active checks