[media] DocBook: fix an unbalanced <para> tag

The </para> got lost on some change at the DVB docbook, making
the tag unbalanced and causing a warning. Fix it.
Signed-off-by: NMauro Carvalho Chehab <mchehab@osg.samsung.com>
Acked-by: NJonathan Corbet <corbet@lwn.net>

Documentation/DocBook/media/dvb/intro.xml

@@ -164,7 +164,7 @@ are called:</para>
 from&#x00A0;0, and M enumerates the devices of each type within each
 adapter, starting from&#x00A0;0, too. We will omit the &#8220;
 <constant>/dev/dvb/adapterN/</constant>&#8221; in the further discussion
-of these devices.
+of these devices.</para>
 
 <para>More details about the data structures and function calls of all
 the devices are described in the following chapters.</para>