[ALSA] hda-codec - Add 6stack model for ALC880

Documentation,HDA Codec driver
- Added a new '6stack' model for ALC880.
- Fixed the typo in 6stack-digout model name.
- Added description for missing models in ALSA-Configuration.txt.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/Documentation/sound/alsa/ALSA-Configuration.txt b/Documentation/sound/alsa/ALSA-Configuration.txt
index 104a994..dfe44cf 100644
--- a/Documentation/sound/alsa/ALSA-Configuration.txt
+++ b/Documentation/sound/alsa/ALSA-Configuration.txt
@@ -636,11 +636,16 @@
 	  3stack-digout	3-jack in back, a HP out and a SPDIF out
 	  5stack	5-jack in back, 2-jack in front
 	  5stack-digout	5-jack in back, 2-jack in front, a SPDIF out
+	  6stack	6-jack in back, 2-jack in front
+	  6stack-digout	6-jack with a SPDIF out
 	  w810		3-jack
 	  z71v		3-jack (HP shared SPDIF)
 	  asus		3-jack
 	  uniwill	3-jack
 	  F1734		2-jack
+	  test		for testing/debugging purpose, almost all controls can be
+			adjusted.  Appearing only when compiled with
+			$CONFIG_SND_DEBUG=y
 
 	CMI9880
 	  minimal	3-jack in back