archlinux: Add polkit to initial package list
archlinux: Add polkit to initial package list

The polkit package is used to let unprivileged users run certain
commands. With it, it is possible to run system commands such as
`poweroff` and `reboot` with an unprivileged user.

Traditionally, only privileged users have access to power management,
but for many desktop setups, you may want to let unprivileged users
perform operations such as shutdown the machine if no other users
are logged in.

GloverDonovan/new-start