[media] DocBook: document DVB net API

The DVB network API was not documented. There are just some
placeholders there.

Replace it by a proper documentation.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
diff --git a/Documentation/DocBook/media_api.tmpl b/Documentation/DocBook/media_api.tmpl
index 1e19451..43eda24 100644
--- a/Documentation/DocBook/media_api.tmpl
+++ b/Documentation/DocBook/media_api.tmpl
@@ -95,12 +95,22 @@
 	<para>For discussing improvements, reporting troubles, sending new drivers, etc, please mail to: <ulink url="http://vger.kernel.org/vger-lists.html#linux-media">Linux Media Mailing List (LMML).</ulink>.</para>
 </preface>
 
-<part id="v4l2spec">&sub-v4l2;</part>
-<part id="dvbapi">&sub-dvbapi;</part>
-<part id="remotes">&sub-remote_controllers;</part>
-<part id="media_common">&sub-media-controller;</part>
+<part id="v4l2spec">
+&sub-v4l2;
+</part>
+<part id="dvbapi">
+&sub-dvbapi;
+</part>
+<part id="remotes">
+&sub-remote_controllers;
+</part>
+<part id="media_common">
+&sub-media-controller;
+</part>
 
-<chapter id="gen_errors">&sub-gen-errors;</chapter>
+<chapter id="gen_errors">
+&sub-gen-errors;
+</chapter>
 
 &sub-fdl-appendix;