Add Xiaomi gateway alarm documentation (#12167)

source/_integrations/alarm_control_panel.xiaomi_miio.markdown

@@ -0,0 +1,39 @@
+---
+title: "Xiaomi Gateway Alarm"
+description: "Instructions on how to integrate your Xiaomi Gateway Alarm within Home Assistant."
+logo: xiaomi.png
+ha_category:
+  - Alarm
+ha_iot_class: Local Polling
+ha_release: 0.110
+ha_domain: xiaomi_miio
+---
+
+The `xiaomi_miio` alarm_control_panel platform allows you to control the state of your Xiaomi Gateway Alarm.
+
+Please follow the instructions on [Retrieving the Access Token](/integrations/vacuum.xiaomi_miio/#retrieving-the-access-token) to get the API token to use during configuration.
+
+## Features
+
+- Turn on/off Alarm
+- See the status of Alarm (armed_away, disarmed, arming)
+
+## Configuration
+
+To set up the Xiaomi gateway, click Configuration in the sidebar, then click Integrations and then click the + icon in the lower right and find xiaomi_miio. Select the option "Connect to a Xiaomi Gateway" and click submit. You will then be presented with a form in which you will need to fill in the "IP address" and 32 characters "token". Optionally, you can specify a different name for the gateway. After you click submit, you will have the opportunity to select the area that your devices are located.
+
+{% configuration %}
+host:
+  description: The IP address of your Xiaomi gateway.
+  required: true
+  type: string
+token:
+  description: The API token of your Xiaomi gateway.
+  required: true
+  type: string
+name:
+  description: The name of your Xiaomi gateway.
+  required: false
+  type: string
+  default: Xiaomi Gateway
+{% endconfiguration %}