badges: Add mapping for neuro-sig FAS membership badge
    
    This commit adds a mapping for the `neuro-sig` FAS group to the
    `neurofedora-sig-member` badge. This is used in an existing cron job
    that automatically awards the badge to members who are already sponsored
    into the FAS group, since the automated rule only awards it to people
    who are added to the group after the badge is pushed.
    
    Signed-off-by: Justin W. Flory <git@jwf.io>