documentation

Pull request #3336: Feature/ZBXNEXT-7744 7.5 D

Merge in WEB/documentation from feature/ZBXNEXT-7744-7.5-D to release/8.0

* commit 'eedeae9f4faef7723cf436334095ead31da2995f':
  ZBXNEXT-7744 fixed a typo.
  ZBXNEXT-7744 minor grammar fixes, fixed a what's new entry and a comment.
  ZBXNEXT-7744 added a what's new entry.
  ZBXNEXT-7744 added new parameters and comments cell content for Redis.
  ZBXNEXT-7744 formatting.