[apm] docs: add deployment annotation example

docs/apm/deployment-annotations.asciidoc

@@ -7,13 +7,40 @@
 ++++
 
 For enhanced visibility into your deployments, we offer deployment annotations on all transaction charts.
-This feature automatically tags new deployments, so you can easily see if your deploy has increased response times
-for an end-user, or if the memory/CPU footprint of your application has changed.
-Being able to identify bad deployments quickly enables you to rollback and fix issues without causing costly outages.
+This feature enables you to easily determine if your deployment has increased response times for an end-user,
+or if the memory/CPU footprint of your application has changed.
+Being able to quickly identify bad deployments enables you to rollback and fix issues without causing costly outages.
+
+By default, automatic deployment annotations are enabled.
+This means the APM app will create an annotation on your data when the `service.version` of your application changes.
+
+Alternatively, you can explicitly create deployment annotations with our annotation API.
+The API can integrate into your CI/CD pipeline,
+so that each time you deploy, a POST request is sent to the annotation API endpoint:
+
+[source,console]
+----
+curl -X POST \
+  http://localhost:5601/api/apm/services/${SERVICE_NAME}/annotation \ <1>
+-H 'Content-Type: application/json' \
+-H 'kbn-xsrf: true' \
+-H 'Authorization: Basic ${API_KEY}' \ <2>
+-d '{
+      "@timestamp": "${DEPLOY_TIME}", <3>
+      "service": {
+        "version": "${SERVICE_VERSION}" <4>
+      },
+      "message": "${MESSAGE}" <5>
+    }'
+----
+<1> The `service.name` of your application
+<2> An APM app API key with sufficient privileges
+<3> The time of the deployment
+<4> The `service.version` to be displayed in the annotation
+<5> A custom message to be displayed in the annotation
+
+See the <<apm-annotation-api,annotation API>> reference for more information.
 
-Deployment annotations are enabled by default, and can be created with the <<apm-annotation-api,annotation API>>.
-If there are no created annotations for the selected time period,
-the APM app will automatically annotate your data if the `service.version` of your application changes.
 
 NOTE: If custom annotations have been created for the selected time period, any derived annotations, i.e., those created automatically when `service.version` changes, will not be shown.