rpc: improve TransactionDescriptionString() "generated" help

src/wallet/rpcwallet.cpp

@@ -1388,7 +1388,7 @@ static const std::vector<RPCResult> TransactionDescriptionString()
 {
     return{{RPCResult::Type::NUM, "confirmations", "The number of confirmations for the transaction. Negative confirmations means the\n"
                "transaction conflicted that many blocks ago."},
-           {RPCResult::Type::BOOL, "generated", /* optional */ true, "Only present if transaction only input is a coinbase one."},
+           {RPCResult::Type::BOOL, "generated", /* optional */ true, "Only present if the transaction's only input is a coinbase one."},
            {RPCResult::Type::BOOL, "trusted", /* optional */ true, "Whether we consider the transaction to be trusted and safe to spend from.\n"
                 "Only present when the transaction has 0 confirmations (or negative confirmations, if conflicted)."},
            {RPCResult::Type::STR_HEX, "blockhash", /* optional */ true, "The block hash containing the transaction."},