Add Electric Kiwi documentation (#25332)

Co-authored-by: Michael Arthur <michael.arthur@propellerhead.co.nz>
Co-authored-by: Franck Nijhof <frenck@frenck.nl>

source/_integrations/electric_kiwi.markdown

@@ -0,0 +1,25 @@
+---
+title: Electric Kiwi
+description: Instructions on how to set up the Electric Kiwi service in Home Assistant.
+ha_category:
+  - Energy
+ha_release: "2023.8"
+ha_iot_class: Cloud Polling
+ha_codeowners:
+  - '@mikey0000'
+ha_domain: electric_kiwi
+ha_config_flow: true
+ha_platforms:
+  - sensor
+ha_integration_type: service
+---
+
+[Electric Kiwi](https://www.electrickiwi.co.nz/) is an independent power and broadband company in New Zealand, offering variable rates for peak, shoulder, and off-peak pricing with a selectable hour of free power. This integration uses the official [Electric Kiwi API](https://developer.electrickiwi.co.nz) to get your account balance and show and select the hour of free power. 
+
+{% include integrations/config_flow.md %}
+
+<div class='note'>
+
+The configuration uses `client_id` and `client_secret` provided to Home Assistant, so all you need to do is install the integration and authenticate using your account credentials. 
+
+</div>