[media] DocBook: add drawing with a typical media device

An illustration of what's considered a typical media device
may help people to better understand the contents of the media
infrastructure API docbook. So, add it.

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 c71ebe3..d15c9c6 100644
--- a/Documentation/DocBook/media_api.tmpl
+++ b/Documentation/DocBook/media_api.tmpl
@@ -60,7 +60,21 @@
 		analog and digital TV receiver cards, AM/FM receiver cards,
 		streaming capture and output devices, codec devices and remote
 		controllers.</para>
-	<para>It is divided into four parts.</para>
+	<para>A typical media device hardware is shown at
+	<xref linkend="typical_media_device" />.</para>
+	<figure id="typical_media_device">
+	    <title>Typical Media Device</title>
+	    <mediaobject>
+		<imageobject>
+		    <imagedata fileref="typical_media_device.svg" format="SVG" />
+		</imageobject>
+		<textobject>
+		    <phrase>Typical Media Device Block Diagram</phrase>
+		</textobject>
+	    </mediaobject>
+	</figure>
+	<para>The media infrastructure API was designed to control such
+	    devices. It is divided into four parts.</para>
 	<para>The first part covers radio, video capture and output,
 		cameras, analog TV devices and codecs.</para>
 	<para>The second part covers the