removing group from default domains and add a warning (#8957)

* removing group from default domains and add a warning

reason:
saying shut down all resulted in disabling all automations

* Minor change

source/_components/google_assistant.markdown

@@ -111,7 +111,6 @@ google_assistant:
   exposed_domains:
     - switch
     - light
-    - group
   entity_config:
     switch.kitchen:
       name: CUSTOM_NAME_FOR_GOOGLE_ASSISTANT
@@ -193,6 +192,10 @@ Currently, the following domains are available to be used with Google Assistant,
 - climate (temperature setting, operation_mode)
 - vacuum (dock/start/stop/pause)
 
+<p class='note warning'>
+  The domain groups contains groups containing all items, by example group.all_automations. When telling Google Assistant to shut down everything, this will lead in this example to disabling all automations
+</p>
+
 ### {% linkable_title Media Player Sources %}
 
 Media Player sources are sent via the Modes trait in Google Assistant.