Unless you were running a VERY ancient version of osTicket then you should already have an ost-config.php. If memory serves me correctly the old settings.php and ostconfig.php file names were used pre 1.7.x. Also at some point the config file was moved from / to /include.
But yes, you should not over write your ost-config.php. You should put it in your /include folder.
Also step 9 in that list is specifically for For versions 1.6 RC1-RC2 Only
. It should also probably say move the file to /include.