CentOS 8 container images do not exclude docs from packages installed (unlike 7)

CentOS 7 seem to have excluded deploying docs:
```
awk '(NF==0&&!done){print "override_install_langs=en_US.utf8\ntsflags=nodocs";done=1}{print}' \
    < /etc/yum.conf > /etc/yum.conf.new
mv /etc/yum.conf.new /etc/yum.conf
```

(From https://github.com/CentOS/sig-cloud-instance-build/blob/master/docker/centos-7-x86_64.ks#L100-L102 )

CentOS 8 doesn't do it - any reason?
