Change the notation H^\star to H^\circledast in the description of RedDSA, to avoid confusion with the ^\star convention for representations of group elements.
Change the notation H^\star to H^\circledast in the description of RedDSA, to avoid confusion with the ^\star convention for representations of group elements.

Signed-off-by: Daira Hopwood <cd7d43d5556a38ce626d53826fddc46adc597539@jacaranda.org>

zcash/zips,zcash/zips,zcash/zips,zcash/zips