media: dvb uAPI docs: get rid of examples section

That section is too outdated and got superseded by DVBv5 and
by libdvbv5.

Maybe some day we'll end adding updated examples there, but
while nobody has time or interest of doing that, just mention
that there and get rid of the current examples for good.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>