Image Repository notes from upgrading off of aad-pod-identity

[defenestration]

https://fluxcd.io/flux/components/image/imagerepositories/#kubelet-identity

I noticed a few things upgrading from aad-pod-identity:

If you are trying to connect to AzureContainerRegistry (ACR) repo, using (or had unspecified) in ImageRepository CRDs spec.provider: generic, you need to use --azure-autologin-for-acr in the args in the image-reflector-controller deployment's container.

If you switch the ImageRepository to spec.provider: azure, then you do not need that flag.

I also noticed the -azure-autologin-for-acr flag is depreciated but it is not documented here. My plan is to use it until I can update all our ImageRepository objects.

I think the upgrade path should be noted, since aad-pod-identity is due to be unsupported in September and users will be migrating off it.