rawtransaction: fix argument in combinerawtransaction help message

src/rpc/rawtransaction.cpp

@@ -627,7 +627,7 @@ static UniValue combinerawtransaction(const JSONRPCRequest& request)
                 {
                     {"txs", RPCArg::Type::ARR, RPCArg::Optional::NO, "The hex strings of partially signed transactions",
                         {
-                            {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A transaction hash"},
+                            {"hexstring", RPCArg::Type::STR_HEX, RPCArg::Optional::OMITTED, "A hex-encoded raw transaction"},
                         },
                         },
                 },