Remove the rule that miners SHOULD NOT mine blocks that chain to other blocks with version number > 4.
Remove the rule that miners SHOULD NOT mine blocks that chain to other blocks with version number > 4.

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

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