readme: playback is broken

Spotify deprecated username and password login. With less than a week of notice. In August. But at least they did provide some notice, which is a huge improvement.

README.rst

@@ -21,8 +21,14 @@ Mopidy-Spotify
 Status  :warning:
 =================
 
+Spotify have recently disabled username and password login for playback
+(`#394 <https://github.com/mopidy/mopidy-spotify/issues/394>`_).
+Alternate authentication methods are possible but not yet supported.
+
 Mopidy-Spotify currently has no support for the following:
 
+- Playback
+
 - Seeking
 
 - Gapless playback
@@ -42,8 +48,6 @@ Mopidy-Spotify currently has no support for the following:
 
 Working support for the following features is currently available:
 
-- Playback
-
 - Search
 
 - Playlists (read-only)