documentation

Pull request #186: Feature/ZBX-21042 6.2 D

Merge in WEB/documentation from feature/ZBX-21042-6.2-D to release/6.2

* commit 'aefbc5d3fad737140816a0f5a038a7a1aac8d25d':
  [ZBX-21042] removed selinux.md page
  changed some wording
  [ZBX-21042] added Selinux package description
  removed unnesessary empty directories (inherited from DokuWiki)