Merge #1516

1516: Default byron-witness-count CLI option to 0 r=intricate a=intricate

Closes #1489. 

Most users probably won't utilize this CLI option, so it makes sense to default it to 0 as opposed to forcing them to specify a value.

Co-authored-by: Luke Nadur <19835357+intricate@users.noreply.github.com>

cardano-cli/src/Cardano/CLI/Shelley/Parsers.hs

@@ -1398,7 +1398,8 @@ pTxByronWitnessCount =
  Opt.option Opt.auto
  ( Opt.long "byron-witness-count"
  <> Opt.metavar "NATURAL"
- <> Opt.help "The number of Byron key witnesses."
+ <> Opt.help "The number of Byron key witnesses (default is 0)."
+ <> Opt.value 0
  )
 
 pQueryFilter :: Parser QueryFilter