Mention 30 days in the past default behavior

doc/api/environments.md

@@ -341,7 +341,8 @@ curl --request DELETE --header "PRIVATE-TOKEN: <your_access_token>" "https://git
 It schedules for deletion multiple environments that have already been
 [stopped](../ci/environments/index.md#stop-an-environment) and
 are [in the review app folder](../ci/review_apps/index.md).
-The actual deletion is performed after 1 week from the time of execution.
+The actual deletion is performed after 1 week from the time of execution. 
+By default, it only deletes environments 30 days or older. You can change this default using the `before` parameter.
 
 ```plaintext
 DELETE /projects/:id/environments/review_apps