[media] DocBook: specify language and encoding for the document

Define the usage of UTF-8 encoding and let clear that the document
is in English.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

Documentation/DocBook/media_api.tmpl

-<?xml version="1.0"?>
+<?xml version="1.0" encoding="UTF-8"?>
 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
 	"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
 <!ENTITY % media-entities SYSTEM "./media-entities.tmpl"> %media-entities;
@@ -33,7 +33,7 @@
 <!ENTITY dash-ent-24            "<entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry><entry>-</entry>">
 ]>
 
-<book id="media_api">
+<book id="media_api" lang="en">
 <bookinfo>
 	<title>LINUX MEDIA INFRASTRUCTURE API</title>