With this patch, completion is provided for `--platform` flags:
docker pull --platform<TAB>
linux linux/amd64 linux/arm/v5 linux/arm/v7 linux/arm64/v8 linux/riscv64 wasip1 windows
linux/386 linux/arm linux/arm/v6 linux/arm64 linux/ppc64le linux/s390x wasip1/wasm windows/amd64
Note that `docker buildx build` (with BuildKit) does not yet provide completion;
it's provided through buildx, and uses a different format (accepting multiple
comma-separated platforms). Interestingly, tab-completion for `docker build`
currently uses completion for non-buildkit, and has some other issues that may
have to be looked into.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>