V4L/DVB (4047): Doc. sources: expose video4linux/

Documentation/video4linux/:
Expose example and tool source files in the Documentation/ directory in
their own files instead of being buried (almost hidden) in readme/txt files.
This will make them more visible/usable to users who may need
to use them, to developers who may need to test with them, and
to janitors who would update them if they were more visible.
Also, if any of these possibly should not be in the kernel tree at
all, it will be clearer that they are here and we can discuss if
they should be removed.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>