Add Elgato Key Light integration (#11391)

* Add Elgato Key Light integration

* ✏️ Tweak

source/_integrations/elgato.markdown

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+---
+title: "Elgato Key Light"
+description: "Instructions on how to integrate an Elgato Key Light with Home Assistant."
+logo: elgato.jpg
+ha_category:
+  - Light
+ha_release: 0.104
+ha_iot_class: Local Polling
+ha_qa_scale: platinum
+---
+
+The [Elgato Key Light](https://www.elgato.com/en/gaming/key-light) sets the
+bar for high-end studio lightning. With 80 LEDs, that put out a massive
+2500 lumens, and can change the color temperature as well.
+
+The LED light panel is created specifically, and designed for streamers
+and content creators, many of whom operate on platforms like YouTube and Twitch.
+
+## Configuration
+
+This integration can be configured using the integrations in the
+Home Assistant frontend.
+
+Menu: **Configuration** -> **Integrations**.
+
+In most cases, Elgato Key Lights devices will be automatically discovered by
+Home Assistant. Those automatically discovered devices are listed
+on the integrations page.
+
+If for some reason (e.g., due to lack of mDNS support on your network),
+the Elgato Key Light isn't discovered, it can be added manually.
+
+Click on the `+` sign to add an integration and click on **Elgato Key Light**.
+After completing the configuration flow, the Key Light integration will be
+available.
+
+## Lights
+
+This integration adds the Key Light device as a light in Home Assistant, and
+allows you to control the color temperature, brightness, and its on/off state.