fix(bil): update doc on voucher scope (scaleway#4037)

Author: jsudraud

console/billing/how-to/redeem-voucher-code.mdx

@@ -7,7 +7,7 @@ content:
   paragraph: Instructions for redeeming a voucher code in the Scaleway console.
 tags: discount voucher billing redeem
 dates:
-  validation: 2024-08-19
+  validation: 2024-11-26
   posted: 2024-02-15
 categories:
   - billing
@@ -23,6 +23,8 @@ Voucher codes are unique and valid only for a defined period.
 - [Owner](/identity-and-access-management/iam/concepts/#owner) status or [IAM permissions](/identity-and-access-management/iam/concepts/#permission) that allow you to perform actions in the intended Organization
 - A valid payment method added to your account.
 
+
+## How to apply a voucher
 1. Click **Billing** in the Organization drop-down menu to go to the **Billing Overview** page.
     <Message type="tip">
       Alternatively, you can reach the [billing page](https://console.scaleway.com/billing/overview) from your [Organization Dashboard](https://console.scaleway.com/organization) by clicking **Go to Billing** above the **Current consumption** area.
@@ -37,4 +39,19 @@ Voucher codes are unique and valid only for a defined period.
       The discount applied can either be a percentage of your monthly invoice or a fixed sum.
     </Message>
 
-    Once the voucher is redeemed, it will appear in the list of your vouchers.
+    Once the voucher is redeemed, it will appear in the list of your vouchers.
+
+## Understanding voucher scope
+Vouchers provide discounts or credits to use on our services. However, certain conditions and exclusions apply to their usage.
+
+### Inclusive and Exclusive vouchers
+- **Incl. (Inclusive)**: The voucher applies only to the products or services listed after "Incl." (e.g., "Incl. PRO2," means that the voucher only applies to PRO2 Instances).
+
+- **Excl. (Exclusive)**: The voucher cannot be applied to the products or services listed after "Excl." (e.g., "Excl. Apple Silicon" means that the voucher does not apply to Apple Silicon machines).
+
+### Fees excluded from vouchers
+Some fees are always excluded from voucher applicability: 
+
+- **Elastic Metal commitment fees**: These are fixed costs for reserving Elastic Metal servers and cannot be covered by vouchers.
+
+- **Domain names**: Fees for registering, renewing, or managing domain names are not eligible for voucher use.