[synthetics] Update alerting docs (#3087)

* add info about configuring alerts

* add to alert options to project config

* address feedback from @paulb-elastic

docs/en/observability/index.asciidoc

@@ -27,7 +27,7 @@ include::{docs-root}/shared/attributes.asciidoc[]
 :shared:               {observability-docs-root}/docs/en/shared
 :kibana-repo-dir:      {kibana-root}/docs
 
-:synthetics_version: v1.0.0
+:synthetics_version: v1.3.0
 :project-monitors: project monitors
 :project-monitors-cap: Project monitors
 :synthetics-app: Synthetics app

docs/en/observability/synthetics-configuration.asciidoc

@@ -208,6 +208,15 @@ with the {kib} URL for the deployment from which to fetch available locations.
 Control the monitor's download speeds, upload speeds, and latency to simulate your application's behavior on slower or laggier networks. Set to `false` to disable throttling altogether.
 `screenshot` (https://github.com/elastic/synthetics/blob/{synthetics_version}/src/common_types.ts#L192[`ScreenshotOptions`])::
 Control whether or not to capture screenshots. Options include `'on'`, `'off'`, or `'only-on-failure'`.
+
+`alert` (https://github.com/elastic/synthetics/blob/{synthetics_version}/src/dsl/monitor.ts#L47-L54[`AlertConfig`])::
+Enable or disable alerts. Read more about alerts in <<synthetics-settings-alerting>>.
++
+`status.enabled` (`boolean`):::
+Enable monitor status alerts.
++
+`tls.enabled` (`boolean`):::
+Enable TLS certificate alerts.
 // end::monitor-config-options[]
 
 For information on configuring monitors individually, refer to <<synthetics-monitor-use>>.

docs/en/observability/synthetics-reference/lightweight-config/common.asciidoc

@@ -182,6 +182,42 @@ a|  Whether to ping using the ipv6 protocol if hostnames are configured.
 ipv6: false
 ----
 
+////////////////////////
+alert
+////////////////////////
+| [[monitor-alert]] *`alert`*
+a| Enable or disable alerts on this monitor. Read more about alerts in <<synthetics-settings-alerting>>.
+
+////////////////////////
+status.enabled
+////////////////////////
+*`status.enabled`* (<<synthetics-lightweight-data-bool,boolean>>)::
+Enable monitor status alerts on this monitor.
++
+*Default*: `true`
++
+*Example*:
++
+[source,yaml]
+----
+alert.status.enabled: true
+----
+
+////////////////////////
+tls.enabled
+////////////////////////
+*`tls.enabled`* (<<synthetics-lightweight-data-bool,boolean>>)::
+Enable TLS certificate alerts on this monitor.
++
+*Default*: `true`
++
+*Example*:
++
+[source,yaml]
+----
+alert.tls.enabled: true
+----
+
 |===
 
 :!hardbreaks-option:

docs/en/observability/synthetics-settings.asciidoc

@@ -10,11 +10,15 @@ There are several Synthetics settings you can adjust in {kib}.
 Alerting enables you to detect complex conditions using *rules* across Observability apps
 and send a notification using *connectors*.
 
-When you create a new synthetic monitor, a new default synthetics rule will be applied.
-To edit the default rule:
+When you create a new synthetic monitor, new default synthetics rules will be applied.
+To edit the default rules:
 
 . Click *Alerts and rules* in the top bar.
-. Click *Monitor status rule* to open a panel where you can edit the rule's configuration.
+. Select a rule to open a panel where you can edit the rule's configuration:
+** *Monitor status rule* for receiving notifications for errors and outages.
+** *TLS certificate rule* for receiving notifications when one or more of your HTTP or TCP
+  lightweight monitors has a TLS certificate expiring within a specified threshold or when
+  it exceeds an age limit.
 
 However, the automatically created Synthetics internal alert is intentionally preconfigured,
 and some configuration options can't be changed.
@@ -24,9 +28,23 @@ If you need specific alerting behavior, set up a different rule.
 To view all existing rules or create a new rule:
 
 . Click *Alerts and rules* in the top bar.
-. Click *Manage rules*.
+. Click *Manage rules* to go to the _Rules_ page.
 
-Read more about creating new rules in <<create-alerts-rules>>.
+On the _Rules_ page, you can manage the default synthetics rules including snoozing rules,
+disabling rules, deleting rules, and more.
+
+[role="screenshot"]
+image::synthetics-settings-disable-default-rules.png[Rules page with default Synthetics rules]
+
+[NOTE]
+====
+You can enable and disable default alerts for individual monitors in a few ways:
+
+* In the {synthetics-app} UI when you <<synthetics-get-started-ui,create a monitor>>.
+* In the {synthetics-app} UI _after_ a monitor is already created, on the *Monitors* page
+  or on the *Edit monitor* page for the monitor.
+* In projects when <<synthetics-lightweight,configuring a lightweight monitor>>.
+====
 
 In the *Alerting* tab on the Synthetics Settings page, you can add and configure connectors.
 If you are running in Elastic Cloud, then an SMTP connector will automatically be configured,