Update webhooks.mdx (#459)

Author: max-koro

docs/developers/using-api/webhooks.mdx

@@ -216,6 +216,7 @@ The first part of the `eventType` will tell you what resources to query in an AP
 | `Account.Closing` | Account is closing |
 | `Account.Closed` | Account was closed |
 | `AccountStatement.Generated` | Account statement was generated and available for download |
+| `AccountStatement.Voided` | Account statement was voided |
 
 ### [Billing](../../topics/accounts/billing/index.mdx) {#events-billing}