documentation

Pull request #2079: Feature/ZBX-25456 7.2 D - Appliance

Merge in WEB/documentation from feature/ZBX-25456-7.2-D to release/7.2

* commit '0a7f69b1a569fbfd8938e3e31d5a4d1b49d3f3d7':
  removed mentions of the non-existing DB user 'zabbix'
  fixed ambiguities
  Added formatting changes (ZBX-25456)
  Improved appliance page (ZBX-25456)
  fixed block IDs
  Further improved the appliance page (ZBX-25456)
  Updated Appliance page (ZBX-25456)
  updated Zabbix appliance page