documentation

Pull request #4282: ZBXNEXT-10468 updated a field descriptions, added a what's new entry.

Merge in WEB/documentation from feature/ZBXNEXT-10468-7.5-D to release/8.0

* commit '371124cdc6388bb9a483ef1b3968b90aa7bde794':
  ZBXNEXT-10468 changed plural to singular, removed redundant link.
  ZZBXNEXT-10468 changed global to user macros.
  ZZBXNEXT-10468 changed user to global macros.
  ZBXNEXT-10468 specified a default value of the {$TRAPPER.ALLOWED_HOSTS}.
  ZBXNEXT-10468 added info about default values, updated screenshots.
  ZBXNEXT-10468 updated a field descriptions, added a what's new entry.