* beefy: add BEEFY 'spec' * Apply suggestions from code review Signed-off-by: Adrian Catangiu <adrian@parity.io> Co-authored-by: Tomasz Drwięga <tomasz@parity.io> Co-authored-by: André Silva <andrerfosilva@gmail.com> Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com> Co-authored-by: parity-processbot <>