util-docker: Adding docker-compose.yaml

"docker-compose.yaml" is used by the docker-compose utility to define
Docker image builds. In the case the "docker-compose.yaml" file defines
the building of all Docker images used in the gem5 project. These can be
built locally using `docker-compose build`.

Change-Id: I2544ec43e3a1743884e5aa243905704cb263d7d9
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/57429
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
2 files changed