Document deprecated demo images
Add descriptions of the deprecated agl-ivi-demo-flutter-simple and
agl-cluster-demo-qtcompositor images that are now only present on
quillback branch.
Bug-AGL: SPEC-5138
Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I3db94158239fb66685cfb371af9656cb3821df85
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/documentation/+/29970
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>
Tested-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>