Update docs

Author: nick-benoit

docs/resources/kibana_security_detection_rule.md

@@ -120,6 +120,7 @@ resource "elasticstack_kibana_security_detection_rule" "advanced" {
 ### Optional
 
 - `actions` (Attributes List) Array of automated actions taken when alerts are generated by the rule. (see [below for nested schema](#nestedatt--actions))
+- `alert_suppression` (Attributes) Defines alert suppression configuration to reduce duplicate alerts. (see [below for nested schema](#nestedatt--alert_suppression))
 - `anomaly_threshold` (Number) Anomaly score threshold above which the rule creates an alert. Valid values are from 0 to 100. Required for machine_learning rules.
 - `author` (List of String) The rule's author.
 - `building_block_type` (String) Determines if the rule acts as a building block. If set, value must be `default`. Building-block alerts are not displayed in the UI by default and are used as a foundation for other rules.
@@ -209,6 +210,28 @@ Required:
 
 
 
+<a id="nestedatt--alert_suppression"></a>
+### Nested Schema for `alert_suppression`
+
+Required:
+
+- `group_by` (List of String) Array of field names to group alerts by for suppression.
+
+Optional:
+
+- `duration` (Attributes) Duration for which alerts are suppressed. (see [below for nested schema](#nestedatt--alert_suppression--duration))
+- `missing_fields_strategy` (String) Strategy for handling missing fields in suppression grouping: 'suppress' - only one alert will be created per suppress by bucket, 'doNotSuppress' - per each document a separate alert will be created.
+
+<a id="nestedatt--alert_suppression--duration"></a>
+### Nested Schema for `alert_suppression.duration`
+
+Required:
+
+- `unit` (String) Duration unit (s, m, h).
+- `value` (Number) Duration value.
+
+
+
 <a id="nestedatt--exceptions_list"></a>
 ### Nested Schema for `exceptions_list`