Update reference/customers.v2.yml

Co-authored-by: Meg Desko <[email protected]>

reference/customers.v2.yml

@@ -1446,7 +1446,7 @@ components:
               maxItems: 1
           - type: array
             title: category, product, or sitewide
-            description: A collection of category-level or product-level discount rules. You can have one or many category or product discount rules.
+            description: A collection of discount rules. You can have one or many category-level or product-level discount rules and one sitewide discount rule.
             items:
                 oneOf:
                   - type: object