setup: print a nicer warning if people didn't specify the right --path
setup: print a nicer warning if people didn't specify the right --path

miguelinux/gummiboot2systemd-boot,todorez/tummiboot,aaronp24/gummiboot,karelzak/gummiboot,freedesktop-unofficial-mirror/gummiboot,liliang365/my_gummiboot,todorez/tummiboot,miguelinux/gummiboot2systemd-boot,liliang365/my_gummiboot,todorez/gummiboot-multiboot2,trilean/gummiboot,freedesktop-unofficial-mirror/gummiboot,aaronp24/gummiboot,trilean/gummiboot,FrozenCow/gummiboot,todorez/gummiboot-multiboot2,karelzak/gummiboot,FrozenCow/gummiboot