docs: join.sh failing in kind tutorial at "docker save" step

[ahmetb]

From https://kubefleet.dev/docs/getting-started/kind/:

./kubefleet/hack/membership/join.sh

docker pull images and load to kind                                                                                                                                                            v0.16.6: Pulling from aks/fleet/member-agent
Digest: sha256:c6ea26d1d7004f0a6edfae26a245c78a75efac3585f56f287b375109068add31                                                                                                                Status: Image is up to date for mcr.microsoft.com/aks/fleet/member-agent:v0.16.6
mcr.microsoft.com/aks/fleet/member-agent:v0.16.6                                                                                                                                               v0.16.6: Pulling from aks/fleet/refresh-token
Digest: sha256:1b01365e4af36f3d56709d78e3ae9d6e481c2f773ed90b78cb2ca0837de95dfd                                                                                                                Status: Image is up to date for mcr.microsoft.com/aks/fleet/refresh-token:v0.16.6
mcr.microsoft.com/aks/fleet/refresh-token:v0.16.6                                                                                                                                              Image: "mcr.microsoft.com/aks/fleet/member-agent:v0.16.6" with ID "sha256:c6ea26d1d7004f0a6edfae26a245c78a75efac3585f56f287b375109068add31" not yet present on node "spoke-control-plane", loading...
ERROR: command "docker save -o /private/var/folders/vs/tl1gmc7532v57hs_zc10y0pw0029gx/T/images-tar2009895273/images.tar mcr.microsoft.com/aks/fleet/member-agent:v0.16.6" failed with error: exit status 1
Command Output: Error response from daemon: unable to create manifests file: NotFound: content digest sha256:63036eb66e21a6e0948af1cf12120c892f520b937811593d3d834b1d69b0c420: not found

I don't know why this step is necessary and why the chart comes imagePullPolicy:Never. kind probably could just pull the images.