ALSA: doc: ReSTize HD-Audio-Models document

A simple reformat with the description list of ReST, and the content
was kept as is, but renamed as Documentation/sound/hd-audio/models.rst.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/Documentation/sound/hd-audio/index.rst b/Documentation/sound/hd-audio/index.rst
index f2dc290..1e8376b 100644
--- a/Documentation/sound/hd-audio/index.rst
+++ b/Documentation/sound/hd-audio/index.rst
@@ -5,3 +5,4 @@
    :maxdepth: 2
 
    notes
+   models