add comments in incremental_auth check

crates/router/src/core/payments/operations/payments_incremental_authorization.rs

@@ -100,6 +100,8 @@ impl<F: Send + Clone>
             .await
             .to_not_found_response(errors::ApiErrorResponse::PaymentNotFound)?;
 
+        // Incremental authorization should be performed on an amount greater than the original authorized amount (in this case, greater than the net_amount which is sent for authorization)
+        // request.amount is the total amount that should be authorized in incremental authorization which should be greater than the original authorized amount
         if payment_attempt.get_total_amount() > request.amount {
             Err(errors::ApiErrorResponse::PreconditionFailed {
                 message: "Amount should be greater than original authorized amount".to_owned(),