Update Huum documentation for new door sensor (#40079)

source/_integrations/huum.markdown

@@ -2,14 +2,17 @@
 title: Huum
 description: Instructions on how to integrate a Huum saunas into Home Assistant.
 ha_category:
+  - Binary sensor
   - Climate
 ha_release: 2024.2
 ha_iot_class: Cloud Polling
 ha_codeowners:
   - '@frwickst'
+  - '@vincentwolsink'
 ha_domain: huum
 ha_config_flow: true
 ha_platforms:
+  - binary_sensor
   - climate
 ha_integration_type: integration
 ---
@@ -28,3 +31,16 @@ sauna by mistake.
 {% endnote %}
 
 {% include integrations/config_flow.md %}
+
+## Available platforms & entities
+
+### Binary sensors
+
+- **Door**: Sauna door state (open or closed).
+
+### Climate
+
+The climate entity controls the sauna heater and offers the following capabilities:
+
+- Adjust target temperature
+- Change operation mode (off or heat)