Add automation example to NUT (#38389)

* Add Automation example documentation

* Apply CodeRabbit suggestions

* Update source/_integrations/nut.markdown

Add sub-heading for Prerequisites in example

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* Update source/_integrations/nut.markdown

Change prerequisites from sentence to bulleted list

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* Update source/_integrations/nut.markdown

Add sub header for YAML example

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* Remove conditions from example

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* Remove description and enquote alias in example

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* Remove mode of single since default

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* Enquote message string

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* Add enquote and lower case to notify title in example

* Clarify device and sensor name

* Clarify example is YAML

* Change comment capitalization to match other requested change

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Co-authored-by: Franck Nijhof <frenck@frenck.nl>

source/_integrations/nut.markdown

@@ -290,6 +290,48 @@ An action is available for each parameterless NUT
 [command](https://networkupstools.org/docs/user-manual.chunked/apcs03.html)
 supported.
 
+## Automation example
+
+Home Assistant {% term automations %} can be created to monitor and
+take actions on one or more power devices using NUT.
+
+The following example illustrates how to use this integration in a
+Home Assistant automation. This example is just a starting point, and
+you can use it as inspiration to create your own automations.
+
+### UPS Power Failure Notification
+
+The following example sends a notification to your mobile device when
+a monitored UPS loses power and begins using the battery.
+
+#### Prerequisites
+
+- The NUT integration must be installed and
+configured.
+- Your mobile device must be configured for
+notification.
+- In the example below, the NUT server device is `ups` with the status
+sensor named `ups_status`. You must change the YAML sensor name to
+match your system.
+
+#### Example in YAML
+
+```yaml
+# Send notification on UPS power failure
+automation:
+  alias: "NUT Power failure notification"
+  triggers:
+    - trigger: state
+      entity_id:
+        - sensor.ups_status
+      to: "On Battery Battery Discharging"
+  actions:
+    - action: notify.notify
+      data:
+        title: "UPS power failure"
+        message: "The UPS lost power and is now on battery"
+```
+
 ## Example resources
 
 Given the following example output from NUT (your variables may differ):