Improve scene docs (#11063)

* Improve scene docs

* Improve examples

source/_integrations/scene.markdown

@@ -24,9 +24,10 @@ scene:
     entities:
       light.tv_back_light:
         state: on
-        brightness: 100
+        brightness: 125
       light.ceiling: off
       media_player.sony_bravia_tv:
+        state: on
         source: HDMI 1
         state: on
 ```
@@ -37,15 +38,15 @@ name:
   required: true
   type: string
 entities:
-  description: Entities to control.
+  description: Entities to control and their desired state.
   required: true
   type: list
 {% endconfiguration %}
 
 As you can see, there are two ways to define the states of each `entity_id`:
 
-- Define the `state` directly with the entity.
-- Define a complex state with its attributes.
+- Define the `state` directly with the entity. Be aware, that `state` needs to be defined.
+- Define a complex state with its attributes. You can see all attributes available for a particular entity under `developer-tools -> state`.
 
 Scenes can be activated using the service `scene.turn_on` (there is no 'scene.turn_off' service).
 
@@ -83,6 +84,7 @@ automation:
           brightness: 100
         light.ceiling: off
         media_player.sony_bravia_tv:
+          state: on
           source: HDMI 1
 ```