chore(observability): Add detailed informations to global config (#976)

Signed-off-by: Alexander Dahmen <alexander.dahmen@inovex.de>

Author: Fyusel

docs/resources/observability_instance.md

@@ -80,7 +80,7 @@ Required:
 
 Optional:
 
-- `global` (Attributes) Global configuration for the alerts. (see [below for nested schema](#nestedatt--alert_config--global))
+- `global` (Attributes) Global configuration for the alerts. If nothing passed the default argus config will be used. It is only possible to update the entire global part, not individual attributes. (see [below for nested schema](#nestedatt--alert_config--global))
 
 <a id="nestedatt--alert_config--receivers"></a>
 ### Nested Schema for `alert_config.receivers`

stackit/internal/services/observability/instance/resource.go

@@ -727,7 +727,7 @@ func (r *instanceResource) Schema(_ context.Context, _ resource.SchemaRequest, r
 						},
 					},
 					"global": schema.SingleNestedAttribute{
-						Description: "Global configuration for the alerts.",
+						Description: "Global configuration for the alerts. If nothing passed the default argus config will be used. It is only possible to update the entire global part, not individual attributes.",
 						Optional:    true,
 						Computed:    true,
 						Attributes: map[string]schema.Attribute{