docs: add a note about promotion types support in Medusa Admin (#10933)

www/apps/resources/app/commerce-modules/promotion/concepts/page.mdx

@@ -72,6 +72,12 @@ A promotion has two types:
   </Table.Body>
 </Table>
 
+<Note>
+
+The Medusa Admin UI may not provide a way to create each of these promotion examples. However, they are supported by the Promotion Module and Medusa's workflows and API routes.
+
+</Note>
+
 ---
 
 ## PromotionRule