BUILD: Simplify enabling journald on installed systems
    
    systemd supports overrides of the standard service file to be placed in
    /etc/systemd/system/<service>.service.d/
    
    With this patch, we will install a commented-out override file to /etc
    that will instruct the user on how to enable logging to journald.
    
    Reviewed-by: Jakub Hrozek <jhrozek@redhat.com>
    Reviewed-by: Lukáš Slebodník <lslebodn@redhat.com>