Support ArchLinux level-2 enroll; Add intune-portal pkg; Add instructions & FAQ

This PR adds necessary package & instructions to support level-2 enrollment on ArchLinux. Manjaro Linux is still pending for testing.

intune-portal/x.install

 post_install() {
         if [ -d /run/systemd/system ] ; then
             systemd-tmpfiles --create intune.conf
+	fi
 
 #            deb-systemd-helper --user enable intune-agent.timer >/dev/null || true
 #            deb-systemd-helper --user enable intune-agent.service >/dev/null || true
@@ -25,7 +26,6 @@ post_install() {
 
         # Restart polkit to get any new authorization actions we put down
         systemctl restart polkit.service 2>/dev/null
-        fi
 	echo "TODO: systemctl enable --now --user intune-agent.timer"
 }