man: use systemd as example instead of udev
man: use systemd as example instead of udev

Nowadays udev doesn't create nodes in /dev anymore. This role is rather
taken by systemd-tmpfiles on early boot so reference it generically as
systemd.

lucasdemarchi/kmod,Distrotech/kmod,pmmccorm/kmod,pmmccorm/kmod,lpereira/kmod,lpereira/kmod,Distrotech/kmod,lucasdemarchi/kmod,lucasdemarchi/kmod,pmmccorm/kmod,Distrotech/kmod,lpereira/kmod