Update aglsetup.sh feature/image help

Update aglsetup.sh feature/image help

Update aglsetup.sh configuration help for move of all demo images
to meta-agl-demo and dropping of separate cluster and telematics
demo features.

Bug-AGL: SPEC-3749

Signed-off-by: Scott Murray <scott.murray@konsulko.com>
Change-Id: I22f4ef610f2562b58b7fc59f777576d6d3d4913c
Reviewed-on: https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl/+/25894
Tested-by: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-build: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
ci-image-boot-test: Jenkins Job builder account <agl-jobbuilder@automotivelinux.org>
Reviewed-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>