Use inst.ks for kickstart on CentOS
Use inst.ks for kickstart on CentOS

It looks like CentOS uses inst.ks now instead
of the ks option.  Updates parameter to latest
one.

Fixes https://github.com/netbootxyz/netboot.xyz/issues/583

antonym/netboot.xyz,antonym/netboot.xyz,antonym/netboot.xyz