documentation

Pull request #3165: feature/DEV-4447-7.5-D. Refined "Installation from packages".

Merge in WEB/documentation from feature/DEV-4447-7.5-D to release/8.0

* commit 'ac7e02a5df58ca72cd24563d8b37656a7105771d':
  [DEV-4447] updated links to agent for Windows & macOS
  [DEV-4447] wording & structure update
  [DEV-4447] small wording update
  [DEV-4447] removed MD note
  [DEV-4447] refined "Installation from packages"