documentation

Pull request #1845: feature/ZBX-17995-6.0-D. Template compatibility in dual-stack environments.

Merge in WEB/documentation from feature/ZBX-17995-6.0-D to release/6.0

* commit 'd415e3f497d13f87e9c5bf292ef610ba6537b11d':
  [ZBX-17995] updated formatting
  [ZBX-17995] updated code block formatting
  [ZBX-17995] updated heading sizes
  [ZBX-17995] template compatibility in dual-stack environments