[media] DVB: dvb-net, make the kconfig text helpful

Telling the user they can disable an option if they want is not the
much useful. Describe what it is good for instead.

The text was derived from Mauro's email.

Signed-off-by: Jiri Slaby <[e-mail]>
Cc: Mauro Carvalho Chehab <[e-mail]>
Cc: Hans Petter Selasky <[e-mail]>
Acked-by: Randy Dunlap <[e-mail]>
Acked-by: Hans Petter Selasky <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/Kconfig

···
 	default (NET && INET)
 	depends on NET && INET && DVB_CORE
 	help
-	  The DVB network support in the DVB core can
-	  optionally be disabled if this
-	  option is set to N.
+	  This option enables DVB Network Support which is a part of the DVB
+	  standard. It is used, for example, by automatic firmware updates used
+	  on Set-Top-Boxes. It can also be used to access the Internet via the
+	  DVB card, if the network provider supports it.
 
-	  If unsure say Y.
+	  You may want to disable the network support on embedded devices. If
+	  unsure say Y.
 
 config VIDEO_MEDIA
 	tristate