[DOCS] Adds missing `monitoring.cluster_alerts.email_notifications.en…

…abled` setting (#127323) (#127388)

* [DOCS] Adds missing  setting

* Removes deprecation message for unsupported version

(cherry picked from commit 27b5735)

docs/settings/monitoring-settings.asciidoc

@@ -31,6 +31,10 @@ For more information, see
 
 [cols="2*<"]
 |===
+| `monitoring.cluster_alerts.email_notifications.enabled`::
+  | deprecated:[7.11.0] 
+  When enabled, sends email notifications for Watcher alerts to the specified email address. The default is `true`. 
+
 | `monitoring.enabled`
   | Set to `true` (default) to enable the {monitor-features} in {kib}. Unlike the
   <<monitoring-ui-enabled, `monitoring.ui.enabled`>> setting, when this setting is `false`, the