rawtransaction: fix argument in combinerawtransaction help message
rawtransaction: fix argument in combinerawtransaction help message

Former-commit-id: 51153b6b23e3bd2d0a458b58e0592cdcc742aded
syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin,syscoin/syscoin