Document new connection options
- authMechanism
- authSource
- gssapiServiceName
- secondaryAcceptableLatencyMS

https://jira.mongodb.org/browse/PHP-1042


git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@333380 c90b9560-bf6c-de11-be94-00142212c4b1