Add fan groups (#19853)

source/_integrations/fan.group.markdown

@@ -0,0 +1,44 @@
+---
+title: "Fan Group"
+description: "Instructions how to setup grouped fans in Home Assistant."
+ha_category:
+  - Fan
+ha_release: 2021.11
+ha_iot_class: Local Push
+ha_quality_scale: internal
+ha_domain: group
+---
+
+The `group` platform can create a fan that combines several fan entities into one.
+
+To enable `Fan Groups` in your installation, add the following to your `configuration.yaml` file:
+
+```yaml
+# Example configuration.yaml entry
+fan:
+  - platform: group
+    entities:
+      - fan.lanai_west
+      - fan.lanai_south
+      - fan.lanai_east
+```
+
+{% configuration %}
+entities:
+  description: List of all fan entities you want to control.
+  required: true
+  type: [string, list]
+name:
+  description: Name to use in the frontend.
+  required: false
+  type: string
+  default: "Fan Group"
+unique_id:
+  description: An ID that uniquely identifies this fan group. If two fans have the same unique ID, Home Assistant will raise an error.
+  required: false
+  type: string
+{% endconfiguration %}
+
+## Functionality
+
+It works best if you group fans with the same supported features together (like support for `percentage`/`direction`/`oscillation`), but is not limited to it. In case you have bundled fans with different features together, the controls will only affect those fans that support the actions.