[media] DocBook/dvbproperty.xml: Fix the units for DTV_FREQUENCY

The units for DTV_FREQUENCY are kHz for satellital delivery systems
(DVB-S/DVB-S2/DVB-TURBO/ISDB-S). Fix it at the API spec.
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

Documentation/DocBook/media/dvb/dvbproperty.xml

@@ -163,14 +163,16 @@ get/set up to 64 properties. The actual meaning of each property is described on
 	<section id="DTV-FREQUENCY">
 		<title><constant>DTV_FREQUENCY</constant></title>
 
-		<para>Central frequency of the channel, in HZ.</para>
+		<para>Central frequency of the channel.</para>
 
 		<para>Notes:</para>
-		<para>1)For ISDB-T, the channels are usually transmitted with an offset of 143kHz.
+		<para>1)For satellital delivery systems, it is measured in kHz.
+			For the other ones, it is measured in Hz.</para>
+		<para>2)For ISDB-T, the channels are usually transmitted with an offset of 143kHz.
 			E.g. a valid frequncy could be 474143 kHz. The stepping is bound to the bandwidth of
 			the channel which is 6MHz.</para>
 
-		<para>2)As in ISDB-Tsb the channel consists of only one or three segments the
+		<para>3)As in ISDB-Tsb the channel consists of only one or three segments the
 			frequency step is 429kHz, 3*429 respectively. As for ISDB-T the
 			central frequency of the channel is expected.</para>
 	</section>