[Discounts] Added missing events (#2981)

Author: mnocon

docs/api/event_reference/discounts_events.md

@@ -19,6 +19,8 @@ The events below are dispatched when managing [discounts](discounts.md):
 |[`CreateDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-CreateDiscountEvent.html)| [`DiscountServiceInterface::createDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_createDiscount) |
 |[`BeforeEnableDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-BeforeEnableDiscountEvent.html)| [`DiscountServiceInterface::enableDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_enableDiscount) |
 |[`EnableDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-EnableDiscountEvent.html)| [`DiscountServiceInterface::enableDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_enableDiscount) |
+|[`BeforeDisableDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-BeforeDisableDiscountEvent.html)| [`DiscountServiceInterface::disableDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_disableDiscount) |
+|[`DisableDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-DisableDiscountEvent.html)| [`DiscountServiceInterface::disableDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_disableDiscount) |
 |[`BeforeDeleteDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-BeforeDeleteDiscountEvent.html)| [`DiscountServiceInterface::deleteDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_deleteDiscount) |
 |[`DeleteDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-DeleteDiscountEvent.html)| [`DiscountServiceInterface::deleteDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_deleteDiscount) |
 |[`BeforeUpdateDiscountEvent`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-Event-BeforeUpdateDiscountEvent.html)| [`DiscountServiceInterface::updateDiscount()`](/api/php_api/php_api_reference/classes/Ibexa-Contracts-Discounts-DiscountServiceInterface.html#method_updateDiscount) |