doc-rst: define PDF's of the media folder

To build only the PDF of the media folder run::

  make SPHINXDIRS=media pdfdocs

Signed-off-by: Markus Heiser <markus.heiser@darmarIT.de>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/media/conf.py b/Documentation/media/conf.py
index 77cb2bb..bef927b 100644
--- a/Documentation/media/conf.py
+++ b/Documentation/media/conf.py
@@ -3,3 +3,8 @@
 project = 'Linux Media Subsystem Documentation'
 
 tags.add("subproject")
+
+latex_documents = [
+    ('index', 'media.tex', 'Linux Media Subsystem Documentation',
+     'The kernel development community', 'manual'),
+]