Customizing a virtual host configuration
From VPS Wiki
As Plesk overwrites changes to httpd.include under certain circumstances, this file is not suitable for permanent changes to the Apache configuration of a particular domain.
Users instead get to rely on vhost.conf which is created in /var/www/vhosts/example.com/conf. After placing the respective Apache configuration commands in vhost.conf, save the file and make sure to activate the changes by entering the command /usr/local/psa/admin/bin/websrvmng -a.
