Add Synthetics settings page

docs/en/observability/synthetics-params-secrets.asciidoc

@@ -36,11 +36,20 @@ journey("My Journey", ({ page, params }) => {
 If you try to run the example above you'll notice an error because we haven't specified a value for the `url` parameter.
 Parameter values can be declared by any of the following methods:
 
-* Declaring a default value for the parameter in a configuration file.
-* Passing the `--params` CLI argument. 
-
-The values in the configuration file are read first, then merged with either the CLI argument,
-with the CLI taking precedence over the configuration file.
+* In the _Global parameters_ tab of the <<synthetics-settings-global-parameters,Synthetics Settings page in {kib}>>.
+* Declaring a default value for the parameter in a <<synthetics-dynamic-configs,configuration file>>.
+* Passing the `--params` <<synthetics-cli-params,CLI argument>>. 
+
+// To do: Need to verify
+The values in the configuration file are read in the following order:
+
+. *Global parameters*: The Global parameters set in {kib} are read first.
+. *Configuration file*: Then the Global parameters are merged with any parameters defined in a configuration file.
+  If a parameter is defined in both {kib} and a configuration file,
+  the value in the configuration file will be used.
+. *CLI*: Then the parameters defined in the configuration are merged with any parameters passed to the CLI `--params` argument.
+  If a parameter is defined in {kib} or a configuration file *and* using the CLI argument,
+  the value defined using the CLI will be used. 
 
 [discrete]
 [[synthetics-dynamic-configs]]

docs/en/observability/synthetics-settings.asciidoc

@@ -1,61 +1,88 @@
 [[synthetics-settings]]
-= Synthetics settings
+= Adjust Synthetics settings
 
 ++++
-<titleabbrev>Settings</titleabbrev>
+<titleabbrev>Adjust settings</titleabbrev>
 ++++
 
+There are several Synthetics settings you can adjust in {kib}.
+
 [discrete]
 [[synthetics-settings-alerting]]
 = Alerting
 
-// to do
-++++
-<div style="background-color:#feedf5;color:#F04E98;height:100px;width:100%;text-align:center;padding-top:35px;margin-top:32px;margin-bottom:32px">
-  To do: Content to be written
-</div>
-++++
+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:
+
+. Click *Alerts and rules* in the top bar.
+. Click *Monitor status rule* to open a panel where you can edit the rule's configuration.
+
+To view all existing rules or create new rule:
+
+. Click *Alerts and rules* in the top bar.
+. Click *Manage rules*.
+
+Read more about creating new rules in <<create-alerts-rules>>.
+
+In the *Alerting* tab on the Synthetics Settings page, you can add and configure connectors.
+Read more about all available connectors in <<action-types-duration>>.
+
+[role="screenshot"]
+image::images/synthetics-settings-alerting.png[Alerting tab on the Synthetics Settings page in {kib}]
 
 [discrete]
 [[synthetics-settings-private-locations]]
 = Private locations
 
-// to do
-++++
-<div style="background-color:#feedf5;color:#F04E98;height:100px;width:100%;text-align:center;padding-top:35px;margin-top:32px;margin-bottom:32px">
-  To do: Content to be written
-</div>
-++++
+Private locations allow you to run monitors from your own premises.
+In the *Private Locations* tab, you can add and manage private locations.
+
+After you <<synthetics-private-location-fleet-agent>> and <<synthetics-private-location-connect>>,
+this is where you will add the private location so you can specify it as the location for
+a monitor created using the Synthetics UI or projects.
+
+[role="screenshot"]
+image::images/synthetics-settings-private-locations.png[Private locations tab on the Synthetics Settings page in {kib}]
 
 [discrete]
 [[synthetics-settings-global-parameters]]
 = Global parameters
 
-// to do
-++++
-<div style="background-color:#feedf5;color:#F04E98;height:100px;width:100%;text-align:center;padding-top:35px;margin-top:32px;margin-bottom:32px">
-  To do: Content to be written
-</div>
-++++
+Global parameters can be defined once and used across the configuration of browser and lightweight monitors.
+
+In the *Global parameters* tab, you can define variables and parameters.
+This is one of several methods you can use to define variables and parameters.
+To learn more about the other methods and which methods take precedence over others, see <<synthetics-params-secrets>>.
+
+[role="screenshot"]
+image::images/synthetics-settings-global-parameters.png[Global parameters tab on the Synthetics Settings page in {kib}]
 
 [discrete]
 [[synthetics-settings-data-retention]]
 = Data retention
 
-// to do
-++++
-<div style="background-color:#feedf5;color:#F04E98;height:100px;width:100%;text-align:center;padding-top:35px;margin-top:32px;margin-bottom:32px">
-  To do: Content to be written
-</div>
-++++
+When you set up a synthetic monitor, data from the monitor is saved in {ref}/data-streams.html[Elasticsearch data streams],
+an append-only structure in Elasticsearch.
+You can customize how long synthetics data is stored by creating your own index lifecycle policy
+and attaching it to the relevant custom Component Template in Stack Management.
+
+In the *Data retention* tab, use the links to jump to the relevant policy for each data stream.
+Learn more about the data included in each data stream in <<synthetics-manage-retention>>.
+
+[role="screenshot"]
+image::images/synthetics-settings-data-retention.png[Data retention tab on the Synthetics Settings page in {kib}]
 
 [discrete]
 [[synthetics-settings-api-keys]]
 = Project API keys
 
-// to do
-++++
-<div style="background-color:#feedf5;color:#F04E98;height:100px;width:100%;text-align:center;padding-top:35px;margin-top:32px;margin-bottom:32px">
-  To do: Content to be written
-</div>
-++++
+Project API keys are used to push monitors remotely from a CLI or CD pipeline.
+
+In the *Project API keys* tab, you can generate project API keys to use with your projects.
+Learn more about using API keys in <<synthetics-get-started-project>>.
+
+[role="screenshot"]
+image::images/synthetics-settings-api-keys.png[Project API keys tab on the Synthetics Settings page in {kib}]