ALSA: doc: Add codecs/index.rst to top-level index

commit 088fb4e ("ALSA: doc: cs35l56: Add information about
Cirrus Logic CS35L54/56/57") added a new subdirectory with an index
file, so this file must be added to the top-level index.

Fixes: 088fb4e ("ALSA: doc: cs35l56: Add information about Cirrus Logic CS35L54/56/57")
Signed-off-by: Richard Fitzgerald <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: rfvirgil

Documentation/sound/index.rst

@@ -13,6 +13,7 @@ Sound Subsystem Documentation
    alsa-configuration
    hd-audio/index
    cards/index
+   codecs/index
    utimers
 
 .. only::  subproject and html