documentation

Pull request #2303: feature/ZBXNEXT-8187-7.0-D: Edited info on host and template groups.

Merge in WEB/documentation from feature/ZBXNEXT-8187-7.0-D to release/7.0

* commit '4ffc68f59f517207116b01130cf4ff2a8fd8b110':
  [ZBXNEXT-8187] Edited page
  [ZBXNEXT-8187] Edited page
  [ZBXNEXT-8187] Added URLs
  [ZBXNEXT-8187] Updated screenshots
  [ZBXNEXT-8187] Added missing bracket
  [ZBXNEXT-8187] Edited info on host and template groups