Add documentation for the Twinkly integration (#15323)

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

source/_integrations/twinkly.markdown

@@ -0,0 +1,28 @@
+---
+title: Twinkly
+description: Instructions on how to integrate Twinkly LED string to Home Assistant.
+ha_category:
+  - Light
+ha_release: 0.119
+ha_config_flow: true
+ha_domain: twinkly
+ha_iot_class: Local pull
+---
+
+The Twinkly integration allows you to control [Twinkly](https://twinkly.com/) LED string from Home Assistant.
+
+The Twinkly devices does not store the effects locally, they are instead re-sent from the Twinkly application each time.
+This means that this integration does not support to change the LED string effect.
+It only supports to configure the brightness and to turn the device on and off.
+
+## Configuration
+
+You can setup this integration from the Home Assistant user interface:
+
+1. In Home Assistant, go to **Configuration > Integrations**.
+1. At the bottom right, click on the **+** button.
+1. In the list select the **Twinkly** integration.
+1. Configure the host (or IP address) of your twinkly device.
+
+   _If configured using an IP address, on your router / DHCP, you should assign a static IP to your Twinkly device._
+