[Logs UI] [Alerting] Documentation (elastic#64886)

* Docs for logs alerts

Co-authored-by: Felix Stürmer <weltenwort@users.noreply.github.com>

docs/logs/index.asciidoc

@@ -17,6 +17,7 @@ In this case, you will only see the logs for the selected component.
 * <<xpack-logs-using>>
 * <<xpack-logs-configuring>>
 * <<xpack-logs-analysis>>
+* <<xpack-logs-alerting>>
 
 [role="screenshot"]
 image::logs/images/logs-console.png[Log Console in Kibana]
@@ -30,3 +31,5 @@ include::using.asciidoc[]
 include::configuring.asciidoc[]
 
 include::log-rate.asciidoc[]
+
+include::logs-alerting.asciidoc[]

docs/logs/logs-alerting.asciidoc

@@ -0,0 +1,27 @@
+[role="xpack"]
+[[xpack-logs-alerting]]
+== Logs alerting
+
+[float]
+=== Overview
+
+To use the alerting functionality you need to {kibana-ref}/alerting-getting-started.html#alerting-setup-prerequisites[set up alerting].
+
+You can then select the *Create alert* option, from the *Alerts* actions dropdown.
+
+[role="screenshot"]
+image::logs/images/alert-actions-menu.png[Screenshot showing alerts menu]
+
+Within the alert flyout you can configure your logs alert:
+
+[role="screenshot"]
+image::logs/images/alert-flyout.png[Screenshot showing alerts flyout]
+
+[float]
+=== Fields and comparators
+
+The comparators available for conditions depend on the chosen field. The combinations available are:
+
+- Numeric fields: *more than*, *more than or equals*, *less than*, *less than or equals*, *equals*, and *does not equal*.
+- Aggregatable fields: *is* and *is not*.
+- Non-aggregatable fields: *matches*, *does not match*, *matches phrase*, *does not match phrase*.