Add NegativeBalanceWarning webhooks in README

README.md

@@ -44,6 +44,7 @@ The library supports all webhooks under the following model directories:
 | [Configuration Webhooks](https://docs.adyen.com/api-explorer/balanceplatform-webhooks/2/overview) | You can use these webhooks to build your implementation. For example, you can use this information to update internal statuses when the status of a capability is changed.                                                                                                          | [configurationwebhooks](src/main/java/com/adyen/model/configurationwebhooks) | **v2**            |
 | [Transfer Webhooks](https://docs.adyen.com/api-explorer/transfer-webhooks/4/overview)             | You can use these webhooks to build your implementation. For example, you can use this information to update balances in your own dashboards or to keep track of incoming funds.                                                                                                    | [transferwebhooks](src/main/java/com/adyen/model/transferwebhooks)           | **v4**            |
 | [Report Webhooks](https://docs.adyen.com/api-explorer/report-webhooks/1/overview)                 | You can download reports programmatically by making an HTTP GET request, or manually from your Balance Platform Customer Area                                                                                                                                                       | [reportwebhooks](src/main/java/com/adyen/model/reportwebhooks)               | **v1**            |
+| [Negative Balance Warning Webhooks](https://docs.adyen.com/api-explorer/Webhooks/1/overview)      | Adyen sends this webhook to inform you about a balance account whose balance has been negative for a given number of days.                                                                                                                                                          | [negativebalancewarningwebhooks](src/main/java/com/adyen/model/negativebalancewarningwebhooks) | **v1**            |
 | [Notification Webhooks](https://docs.adyen.com/api-explorer/Webhooks/1/overview)                  | We use webhooks to send you updates about payment status updates, newly available reports, and other events that you can subscribe to. For more information, refer to our documentation                                                                                             | [notification](src/main/java/com/adyen/model/notification)                   | **v1**            |
 | [Management Webhooks](https://docs.adyen.com/api-explorer/ManagementNotification/3/overview)      | Adyen uses webhooks to inform your system about events that happen with your Adyen company and merchant accounts, stores, payment terminals, and payment methods when using Management API                                                                                          | [managementwebhooks](src/main/java/com/adyen/model/managementwebhooks)       | **v3**            |
 | [Classic Platform Webhooks](https://docs.adyen.com/api-explorer/Notification/6/overview#retry)    | The Notification API sends notifications to the endpoints specified in a given subscription. Subscriptions are managed through the Notification Configuration API. The API specifications listed here detail the format of each notification.                                       | [marketpaywebhooks](src/main/java/com/adyen/model/marketpaywebhooks)         | **v6**            |