Update media_player.markdown (home-assistant#2656)

Andreas Ahrens · Landrash · commit e0ab75a8cb21 · 2017-05-19T08:58:17.000+02:00
Changed shuffle_set from 'source' to 'shuffle'
diff --git a/source/_components/media_player.markdown b/source/_components/media_player.markdown
@@ -71,4 +71,4 @@ Currently only supports Spotify.
 | Service data attribute | Optional | Description                                          |
 | ---------------------- | -------- | ---------------------------------------------------- |
 | `entity_id`            |       no | Target a specific media player. For example `media_player.spotify`|
-| `source`               |       no | `true`/`false` for enabling/disabling shuffle            |
+| `shuffle`               |       no | `true`/`false` for enabling/disabling shuffle            |
