Add select configuration entry docs for Cambridge Audio (#35254)

* Add select configuration entry docs for Cambridge Audio

* Use dash for list for Cambridge Audio

source/_integrations/cambridge_audio.markdown

@@ -3,12 +3,14 @@ title: Cambridge Audio
 description: Instructions on how to integrate Cambridge Audio Receivers into Home Assistant.
 ha_category:
   - Media player
+  - Select
 ha_release: '2024.10'
 ha_iot_class: Local Push
 ha_domain: cambridge_audio
 ha_platforms:
   - diagnostics
   - media_player
+  - select
 ha_codeowners:
   - '@noahhusby'
 ha_config_flow: true
@@ -46,6 +48,11 @@ Host:
     type: string
 {% endconfiguration_basic %}
 
+## Available configuration entities
+
+The integration provides a few entities to configure the device settings. The following entities are supported:
+- Display brightness
+
 ## Troubleshooting
 
 ### The buttons to skip, shuffle, and repeat the track are missing