SYSTEMDCOMPAT no longer exists, README.md needs updating

[LW-archlinux]

The SYSTEMDCOMPAT makefile flag was removed in M4 patch , commit fd95fce

It appears a similar result can be achieved with HAVESYSTEMD and HAVEOPENRC .
Please update README.md .

[artixnous]

We don't monitor Github anymore, we only use it for backup purposes of our gitea repositories. Please, use our forum or the artix-general mailing list for raising issues (you can post to it without subscription, only you won't get emails from it and your message will have to be approved first).