archlinux: Enable the lxdm service

Note that we enable lxdm before revoking privileges. The user can
start lxdm manually after this script is finished, but ideally the
system should first be rebooted to ensure that any kernel updates
are applied properly.

.archlinux/bootstrap.sh

@@ -35,6 +35,9 @@ yay -S shantz-xwinwrap-bzr
 make fontconfig
 make yarnconfig
 
+# Enable the lightweight X11 display manager
+systemctl enable --now lxdm.service
+
 # Revoke privileges
 sudo -K