documentation

Pull request #1987: feature/ZBX-23664-7.0-D. updated Agent interface availability behavior for active checks.

Merge in WEB/documentation from feature/ZBX-23664-7.0-D to release/7.0

* commit 'edc3e4d6bef3e7ab89eb97112379024f223e7b42':
  [ZBX-23664] StartPollers → StartAgentPollers
  [ZBX-23664] updated Agent interface availability behavior for active checks
  [ZBX-23664] minor wording refinement
  [ZBX-23664] updated Agent interface availability behavior for active checks
  [ZBX-23664] improved host availability description/readability