Update default-billing-currency.mdx

update to clarify default currency is synced to Stripe

Author: clairekinde11

src/content/docs/billing/get-started/default-billing-currency.mdx

@@ -8,7 +8,9 @@ relatedArticles:
   - e6dde80d-2977-419f-a05a-62ad0a7ac6de
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-You need to set a default billing currency for all your Kinde plans, before you create them. The currency you select cannot be changed after your first plan is published. For now, the default billing currency will be used in all plans and plan groups you create. 
+You need to set a default billing currency for all your Kinde plans, before you create them. This is the currency that purchase transactions will be processed in Stripe.
+
+The currency you select cannot be changed after your first plan is published. For now, the default billing currency will be used in all plans and plan groups you create. 
 
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