Doc for EKS Pod Identity permission model

[sw360cab]

What would you like to be added:

I have successfully setup ExternalDNS operator in an EKS cluster relying EKS Pod Identity, the most recent method, which replaces IRSA permission model in AWS EKS clusters.

Why is this needed:

I have seen that only the IRSA Permission model is listed in the doc.
I was wondering if this is because EKS Pod Identity only works with AWS EKS clusters, or it may be useful I work on a PR to describe in the official doc how to achieve that.

[AlbertHahn]

I would be very interested for the documentation regarding how to setup external-dns with pod identity. Could you already share your PR?

[vflaux]

It’s probably not documented because the IRSA docs were written before Pod Identity existed, and nobody’s updated them since. 😄
It would definitely be nice to have.

[sw360cab]

Working on it