Update media_player.onkyo.markdown (#529)

Updated to reflect updates in 0.20

source/_components/media_player.onkyo.markdown

@@ -21,12 +21,20 @@ To add an Onkyo receiver to your installation, add the following to your `config
 # Example configuration.yaml entry
 media_player:
   platform: onkyo
+  host: 192.168.1.2
+  name: receiver
+  sources:
+    pc: 'HTPC'
+    aux1: 'Chromecast'
+    bd: 'Bluray'
+    game: 'Wii U'
 ```
+Configuration variables:
+- **host** (*Optional*): IP address of the device. Example:`192.168.1.2` If not specified, the platform will load any discovered receivers.
+- **name** (*Optional, required if host is specified*): Name of the device
+- **sources** (*Optional*): A list of mappings from source to source name. Valid sources can be found below. A default list will be used if no source mapping is specified.
 
-A few notes:
-
-Source selection has no front-end UI, but can be controlled by way of service calls. Select the source string from the following list:
-
+List of source names:
 - video1
 - video2
 - video3
@@ -53,41 +61,3 @@ Source selection has no front-end UI, but can be controlled by way of service ca
 - multi-ch
 - xm
 - sirius
-
-Sample automation and input select
-
-```yaml
-automation:
-  alias: Receiver Source
-  trigger:
-    platform: state
-    entity_id: input_select.receiver_source
-  action:
-    service: media_player.select_source
-    data_template:
-      entity_id: media_player.txnr535_000000000000
-      source: >
-        {% raw %}{% if is_state('input_select.receiver_source', 'HTPC') %}
-          pc
-        {% elif is_state('input_select.receiver_source', 'Chromecast') %}
-          aux1
-        {% elif is_state('input_select.receiver_source', 'Wii U') %}
-          game
-        {% elif is_state('input_select.receiver_source', 'Bluray') %}
-          bd
-        {% elif is_state('input_select.receiver_source', 'Raspberry Pi') %}
-          tv
-        {% endif %}{% endraw %}
-        
-input_select:
-  receiver_source:
-    name: Source
-    options:
-      - HTPC
-      - Chromecast
-      - Wii U
-      - Bluray
-      - Raspberry Pi
-    initial: None
-```
-