documentation

Pull request #1077: Feature/ZBXNEXT-8330 6.4 D

Merge in WEB/documentation from feature/ZBXNEXT-8330-6.4-D to release/6.4

* commit 'c2a7b7ce72ae2a38d15501c6983163c962a911e5':
  fixed some typos
  [ZBXNEXT-8330] added Supported since note to Default parameters
  [ZBXNEXT-8330] fixed some inconsistencies
  [ZBXNEXT-8330] minor rephrasing
  [ZBXNEXT-8330] formatting fixes
  [ZBXNEXT-8330] multiple page improvements
  [ZBXNEXT-8330] plugins support default parameters
  minor rephrasing
  [ZBXNEXT-8330] updated Memchached, MongoDB, MySQL, Oracle, Redis plugin params
  [ZBXNEXT-8330] added Ceph configuration parameters
  [ZBXNEXT-8330] Default.* plugin parameters
  [ZBXNEXT-8330] updated plugins page
  [ZBXNEXT-8330] new default parameters for Zabbix agent 2