Add sony songpal docs (#4570)

* add sony songpal docs

* use configuration, add a title for configuration section

* remove oxford comma, add link to media_player's services

* add entity_id desc for service

* be more descriptive which devices are supported

* Update songpal supported devices + bump version

* discoverY

* Update media_player.songpal.markdown

* Fix invalid syntax

source/_components/media_player.songpal.markdown

@@ -0,0 +1,68 @@
+---
+layout: page
+title: "Sony SongPal compatible devices"
+description: "Instructions how to integrate Sony Songpal devices into Home Assistant."
+date: 2018-02-03 09:00
+sidebar: true
+comments: false
+sharing: true
+footer: true
+logo: sony.png
+ha_category: Media Player
+ha_iot_class: "Local Polling"
+ha_release: 0.65
+---
+
+The `songpal` platform allows you to control Sony's Songpal ("[Audio Control API](https://developer.sony.com/develop/audio-control-api/)") compatible devices such as soundbars, AV receivers and wireless speakers from Home Assistant.
+
+Even when the API officially supports only a few devices (HT-ST5000, HT-MT500, HT-CT800, SRS-ZR5 and STR-DN1080), it has also been confirmed to work on others. [The list of supported devices](http://vssupport.sony.net/en_ww/device.html) from Sony's Songpal website lists devices which are likely to be compatible with this platform.
+
+If the platform works with your non-listed device, or you encounter bugs, please feel free to [report them upstream](https://github.com/rytilahti/python-songpal).
+
+A few notes:
+
+- The quick start-up mode has to be enabled in order to turn the device on.
+- Supports currently only one output terminal, i.e. the volume control works only on the first volume controller as reported by the backend library.
+- Some devices, e.g. HT-XT3, do not support decreasing the volume step-by-step correctly.
+- Feel free to improve the available services!
+
+## {% linkable_title Configuration %}
+
+The platform will be loaded automatically by discovery component. If you want to manually configure it, add the following to your `configuration.yaml` file:
+
+```yaml
+media_player:
+  - platform: songpal
+    name: my soundbar
+    endpoint: http://IP_ADDRESS:10000/sony
+```
+
+{% configuration %}
+name:
+  description: The name to display for this device.
+  required: false
+  type: string
+endpoint:
+  description: API endpoint of the device.
+  required: true
+  type: string
+{% endconfiguration %}
+
+See [python-songpal's documentation](https://github.com/rytilahti/python-songpal#locating-the-endpoint) how to get your API endpoint.
+
+## {% linkable_title Services %}
+
+In addition to the general [media player services](https://home-assistant.io/components/media_player/#services), the following services are provided:
+
+### {% linkable_title Service `media_player/songpal_set_sound_setting` %}
+
+For a list of available settings and their values use [`songpal sound`](https://github.com/rytilahti/python-songpal#sound-settings) command.
+
+| Service data attribute | Optional | Description                                      |
+|------------------------|----------|--------------------------------------------------|
+| `entity_id`            |      yes | Target entity, leave unset for all devices       |
+| `name`                 |       no | Configuration variable, e.g. `nightmode`         |
+| `value`                |       no | New configuration value, e.g. `on`               |
+
+
+