3_Developer_Guides/5_General_setup: Simple docs for video camera streaming

3_Developer_Guides/5_General_setup: Simple docs for video camera streaming

This mostly targets rpi4 as a camera and display are rather easy to get
by, but also vivid testing module which can also be used from h3ulcb.

Bug-AGL: SPEC-4170

Signed-off-by: Marius Vlad <marius.vlad@collabora.com>
Change-Id: Id76c2a2bf5c1156de70c906c0534c36b36af30c4
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/documentation/+/27134
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>