9042cb143b
DOCKER_BUILDKIT=1 in the build workflow only works if the host has the buildx CLI plugin installed. Bare docker-ce sometimes ships without it (Debian/Ubuntu separate packaging). Document the install so future hosts onboarding to be build targets don't hit the same 'BuildKit is enabled but the buildx component is missing' error. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>