docs: clarify legacy managed alerts enables all preconfigured alerts

Author: jremy42

internal/services/cockpit/alert_manager.go

@@ -33,7 +33,7 @@ func ResourceCockpitAlertManager() *schema.Resource {
 				Optional:    true,
 				Computed:    true,
 				Deprecated:  "Use 'preconfigured_alert_ids' instead. This field will be removed in a future version.",
-				Description: "Enable or disable the alert manager (deprecated)",
+				Description: "Enable or disable the alert manager (deprecated). When set to true, it enables all preconfigured alerts for the project. You cannot filter or disable individual alerts with this legacy flag.",
 			},
 			"preconfigured_alert_ids": {
 				Type:             schema.TypeSet,

templates/resources/cockpit_alert_manager.md.tmpl

@@ -91,7 +91,7 @@ resource "scaleway_cockpit_alert_manager" "alert_manager" {
 This section lists the arguments that are supported:
 
 - `preconfigured_alert_ids` - (Optional, Set of String) A set of preconfigured alert rule IDs to enable explicitly. Use the [`scaleway_cockpit_preconfigured_alert`](../data-sources/cockpit_preconfigured_alert.md) data source to list available alerts.
-- `enable_managed_alerts` - **Deprecated** (Optional, Boolean) Use `preconfigured_alert_ids` instead. This field will be removed in a future version.
+- `enable_managed_alerts` - **Deprecated** (Optional, Boolean) Use `preconfigured_alert_ids` instead. This field will be removed in a future version. When set to `true`, it enables *all* preconfigured alerts for the project. You cannot filter or disable individual alerts with this legacy flag.
 - `contact_points` - (Optional, List of Map) A list of contact points with email addresses that will receive alerts. Each map should contain a single key `email`.
 - `project_id` - (Defaults to the Project ID specified in the [provider configuration](../index.md#project_id)) The ID of the Project the Cockpit is associated with.
 - `region` - (Defaults to the region specified in the [provider configuration](../index.md#arguments-reference)) The [region](../guides/regions_and_zones.md#regions) where the [alert manager](https://www.scaleway.com/en/docs/observability/cockpit/concepts/#alert-manager) should be enabled.