documentation

Pull request #2279: Feature/ZBX-23850 7.2 D

Merge in WEB/documentation from feature/ZBX-23850-7.2-D to release/7.2

* commit 'c4ad8b8aee1734f22dfa8a8bedbb3ea1f6c05a40':
  ZBX-23850 changed the arrows.
  ZBX-23850 added more notes to the Interface parameter.
  ZBX-23850 added description of the blk requests behavior.
  ZBX-23850 Added more information of the required fields, corrected a file path and name, corrected a key formatting.