Add 'LOGO' to os-release(5) for Fedora
    
    A number of desktop environments (including GNOME and Pantheon)
    want to use this attribute for identifying the distribution logo
    instead of requiring to be patched to locate our logo icon since
    this is now a valid, specified property in os-release(5)
    since systemd 240.
    
    Signed-off-by: Neal Gompa <ngompa13@gmail.com>