Add a note about docker compose version

Dockerfile

@@ -20,6 +20,7 @@ ARG GIT_EXTRAS_VERSION=7.1.0
 ARG GLAB_VERSION=1.36.0
 ARG apkArch
 ARG buildx_version=0.12.1
+# IMPORTANT: keep the docker compose version in sync with the Ansible Docker role.
 ARG compose_version=2.24.6
 ARG composer_version=2.7.1
 ARG dockerArch