"systemctl enable --user" incorrectly relies on multi-user.target

[emersonrp]

On at least some distributions, there's no "multi-user.target" for user systemd units. The file that ends up at /usr/lib/systemd/user/mpd-discord.service should contain "default.target" in place of "multi-user.target" in the [Install] section.

As it is, "systemctl enable --user mpd-discord.service" will throw a warning and the service will not start at login time as intended.