Clarify the definition of pad in \crossref{concretesinsemillahash} by disambiguating M^pieces from M^padded.
Clarify the definition of pad in \crossref{concretesinsemillahash} by disambiguating M^pieces from M^padded.

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

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