[8.15](backport #4113) Port EEM and new services experience docs to stateful

docs/en/observability/apm-ui/index.asciidoc

@@ -45,6 +45,8 @@ Configure and troubleshoot the APM UI:
 
 include::services.asciidoc[leveloffset=-1]
 
+include::new-experience-services.asciidoc[leveloffset=+2]
+
 include::traces.asciidoc[leveloffset=-1]
 
 include::dependencies.asciidoc[leveloffset=-1]

docs/en/observability/apm-ui/new-experience-services.asciidoc

@@ -0,0 +1,51 @@
+[[new-experience-services]]
+= New services experience
+
+preview::[]
+
+With this technical preview,
+Elastic expands the **Services** inventory to include services found in logs.
+This means you can monitor the services you care about even if you only have logs
+and aren't ready to instrument your services.
+
+The new **Services** inventory shows services instrumented with APM or OpenTelemetry,
+plus any services declared using `service.name` in your logs:
+
+[role="screenshot"]
+image::images/entity-centric-services-inventory.png[Services inventory that shows APM data and log data]
+
+For instrumented services that also have custom logs, the APM and log data are displayed in the same view.
+For services that only have log data,
+the log data is displayed, and you have the option of adding APM later.
+
+NOTE: The new **Services** inventory requires the Elastic Entity Model (EEM). To learn more, refer to <<elastic-entity-model>>.
+
+[discrete]
+== Turn on the new experience
+
+The new services experience is turned off by default. To turn it on:
+
+. Go to **{observability}** → **APM** → **Services**.
+. Click **Try out Elastic's new experience!**
+
+If you have the correct privileges, the EEM will be turned on automatically.
+Otherwise, you need to ask your administrator to turn on this feature under **Stack Management**.
+
+To turn off the new experience, click **Restore classic view**.
+You can switch back and forth between the new and classic views whenever you want.
+
+****
+**Does turning on the new experience affect other users?**
+
+No. The settings are applied at the browser level,
+which means that other users need to turn on the new experience if they want to use it.
+****
+
+[discrete]
+== Add services to the inventory
+
+To add services to the inventory, use one of the following approaches:
+
+* Instrument your services with APM or OpenTelemetry.
+To learn how, refer to <<traces-get-started>>.
+* Declare `service.name` in your logs. To learn how, <<add-logs-service-name>>.

docs/en/observability/apm-ui/services.asciidoc

@@ -14,6 +14,8 @@ In addition to health status, active alerts for each service are prominently dis
 [role="screenshot"]
 image::./images/apm-services-overview.png[Example view of services table the APM UI in Kibana]
 
+TIP: Want to monitor service logs without instrumenting all your services? Learn about our <<new-experience-services>>.
+
 [float]
 [[service-groups]]
 ==== Service groups

docs/en/observability/elastic-entity-model.asciidoc

@@ -0,0 +1,67 @@
+[[elastic-entity-model]]
+= Elastic Entity Model
+
+preview::[]
+
+The Elastic Entity Model consists of:
+
+* a data model and related entity indices
+* an Entity Discovery Framework, which consists of {ref}/transforms.html[transforms] and {ref}/ingest.html[Ingest pipelines] that read from signal indices and write data to entity indices
+* a set of management APIs that empower entity-centric Elastic solution features and workflows
+
+In the context of Elastic Observability,
+an _entity_ is an object of interest that can be associated with produced telemetry and identified as unique.
+Note that this definition is intentionally closely aligned to the work of the https://github.com/open-telemetry/oteps/blob/main/text/entities/0256-entities-data-model.md#data-model[OpenTelemetry Entities SIG].
+Examples of entities include (but are not limited to) services, hosts, and containers.
+
+The concept of an entity is important as a means to unify observability signals based on the underlying entity that the signals describe.
+
+[NOTE]
+====
+* The Elastic Entity Model currently supports the <<new-experience-services,new service inventory experience>> limited to service-based entities (as identified by `service.name`) located in data identified by `logs-*` and `filebeat*` index patterns
+* During Technical Preview, Entity Discovery Framework components are not enabled by default
+====
+
+[discrete]
+== Enable the Elastic Entity Model
+
+During Technical Preview,
+the Elastic Entity Model is enabled when you turn on the entity-centric service inventory described in <<new-experience-services>>.
+
+The following {es} privileges are required:
+
+[cols="1,1"]
+|====
+|**Index privileges**
+|names: [`.entities*`], privileges: [`create_index`, `index`, `create_doc`, `auto_configure`, `read`]
+
+names: [`logs-*`, `filebeat*`, `metrics-*`, `metricbeat*`, `traces-*`, `.entities*`], privileges: [`read`, `view_index_metadata`]
+
+|**Cluster privileges**
+|`manage_transform`, `manage_ingest_pipelines`, `manage_index_templates`
+
+|**Application privileges**
+|application: `kibana-.kibana`, privileges: [`saved_object:entity-definition/*`, `saved_object:entity-discovery-api-key/*`], resources: [*]
+|====
+
+For more information, refer to {ref}/security-privileges.html[Security privileges] in the {es} documentation.
+
+[discrete]
+== Disable the Elastic Entity Model
+
+From the Dev Console, run the command: `DELETE kbn:/internal/entities/managed/enablement`
+
+The following {es} privileges are required to delete {es} resources:
+
+[cols="1,1"]
+|====
+|**Index privileges**
+|names: [`.entities*`], privileges: [`delete_index`]
+
+|**Cluster privileges**
+|`manage_transform`, `manage_ingest_pipelines`, `manage_index_templates`
+
+|**Application privileges**
+|application: `kibana-.kibana`, privileges: [`saved_object:entity-definition/delete`, `saved_object:entity-discovery-api-key/delete`], resources: [*]
+|====
+

docs/en/observability/index.asciidoc

@@ -205,8 +205,15 @@ include::exploratory-data-visualizations.asciidoc[leveloffset=+2]
 
 include::inspect.asciidoc[leveloffset=+2]
 
+// Reference
+include::reference.asciidoc[leveloffset=+1]
+
 // Fields
-include::fields-reference.asciidoc[leveloffset=+1]
+include::fields-reference.asciidoc[leveloffset=+2]
+
+// Elastic Entity Model
+
+include::elastic-entity-model.asciidoc[leveloffset=+2]
 
 // Tutorials
 include::tutorials.asciidoc[]

docs/en/observability/reference.asciidoc

@@ -0,0 +1,9 @@
+[[reference]]
+= Reference
+
+This section contains reference information related to using Elastic {observability}.
+
+* <<fields-reference>>
+* <<elastic-entity-model>>
+
+