media: docs: update Digital TV faq.rst

This file contains lots of obsoleted information. Update it
to reflect the current status and tools used by Digital TV
users and add pointers to the current locations and to
LinuxTV wiki pages.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

media: docs: move user-facing docs to the admin guide

Most of the driver-specific documentation is meant to help
users of the media subsystem.

Move them to the admin-guide.

It should be noticed, however, that several of those files
are outdated and will require further work in order to make
them useful again.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>