documentation

[ZBXNEXT-3100] Users required to enter current password when changing their own password.

Merge in WEB/documentation from feature/ZBXNEXT-3100-6.4-D to release/6.4

* commit '0b7acffa6f92d5bc6220fb0ea90bd78a38143b13':
  [ZBXNEXT-3100] Updated page "What's new"
  [ZBXNEXT-3100] Updated formulations in multiple pages
  [ZBXNEXT-3100] Updated formulations in multiple pages
  [ZBXNEXT-3100] Updated page: "What's new"
  [ZBXNEXT-3100] Updated page: "User settings"
  [ZBXNEXT-3100] Updated page: "Configuring a user"