Update pay-invoices-overdue-balances.mdx (#24904)

Syntax fix :::warn > :::caution

Author: simon-says

src/content/docs/billing/pay-invoices-overdue-balances.mdx

@@ -23,7 +23,7 @@ You can pay your entire balance in one transaction, or if you have multiple invo
 
 ## Understand why you have an outstanding balance
 
-:::warn
+:::caution
 Please note that some unpaid invoices may not be visible. These unpaid invoices will still prevent account modifications. In these cases you should [contact Cloudflare Support](/support/contacting-cloudflare-support/).
 :::