Add documentation for the new moehlenhoff_alpha2 integration (#21328)

Co-authored-by: Simon Hansen <67142049+DurgNomis-drol@users.noreply.github.com>
Co-authored-by: Franck Nijhof <git@frenck.dev>

source/_integrations/moehlenhoff_alpha2.markdown

@@ -0,0 +1,51 @@
+---
+title: Möhlenhoff Alpha 2
+description: Instructions on how to integrate a Möhlenhoff Alpha 2 temperature control system into Home Assistant.
+ha_category: Climate
+ha_release: 2022.3
+ha_iot_class: Local Polling
+ha_config_flow: true
+ha_codeowners:
+  - '@j-a-n'
+ha_domain: moehlenhoff_alpha2
+ha_platforms:
+  - climate
+---
+
+The Möhlenhoff Alpha 2 integration allows you to control a
+[Möhlenhoff Alpha 2](https://www.moehlenhoff.de/en/products/room-by-room-control/oem-alpha-2-system)
+temperature control system.
+
+## Prerequisites
+
+Please make sure the base station is turned on and connected to your local network.
+
+
+{% include integrations/config_flow.md %}
+
+## Climate
+
+The  climate platform provides current and target temperature information,
+HVAC and preset mode.
+
+A climate entity will be created for each area. The name of the entity is
+taken from the name of the heat area defined in the Alpha 2 base station.
+
+The state is polled from the base every 60 seconds.
+
+Please note that after changing the temperature in Home Assistant,
+it may take up to 10 minutes for your room control units to display these
+changes.
+
+### Integration services
+
+This integration supports the following services (see [Climate](/integrations/climate/)).
+
+- [`set_temperature`](/integrations/climate/#service-climateset_temperature)
+- [`set_hvac_mode`](/integrations/climate/#service-climateset_hvac_mode)
+  - `heat` for heating mode
+  - `cool` for cooling mode
+- [`set_preset_mode`](/integrations/climate/#service-climateset_preset_mode)
+  - `auto` enable schedule based operation
+  - `day` enable day mode
+  - `night` enable night mode