documentation

[DEV-2351] plugins now use the same version as Zabbix itself

Merge in WEB/documentation from feature/DEV-2351-6.0-D to release/6.0

* commit 'b1bdedcf91f20f108fb28276f55bd8a02918a525':
  whatsnew6013.md fixed plugin version error
  [DEV-2351] plugins now use the same version as Zabbix itself