docs-rst: add sound book to pdf output

The sound subsystem book was added without the bits required to
generate PDF output. Add them.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/Documentation/conf.py b/Documentation/conf.py
index 1d461f0c1cd0..bca751960dec 100644
--- a/Documentation/conf.py
+++ b/Documentation/conf.py
@@ -371,6 +371,8 @@ latex_documents = [
      'The kernel development community', 'manual'),
     ('security/index', 'security.tex', 'The kernel security subsystem manual',
      'The kernel development community', 'manual'),
+    ('sound/index', 'sound.tex', 'Linux Sound Subsystem Documentation',
+     'The kernel development community', 'manual'),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of