Document Assume Role usage for EKS provider

[clstokes]

Problem description

When a user tries to use assume role with https://github.com/pulumi/pulumi-eks, they get an error message about the cluster being "unreachable". We added support for assume role with EKS at #140 with CreationRoleProvider but this is not easily discoverable.

Example Error Message

kubernetes:core:ConfigMap (eks-cluster-nodeAccess):
  error: configured Kubernetes cluster is unreachable: unable to load schema information from the API server: the server has asked for the client to provide credentials

Suggestions for a fix

• Add an EKS-specific note about CreationRoleProvider to https://www.pulumi.com/docs/intro/cloud-providers/kubernetes/setup/. And eventually other providers as needed.
• Link to that page in the error message - i.e.

  kubernetes:core:ConfigMap (eks-cluster-nodeAccess):
    error: configured Kubernetes cluster is unreachable: unable to load schema information from the API 
  server: the server has asked for the client to provide credentials. See LINK for more details.
  

• Add an "Authentication" note to https://www.pulumi.com/docs/reference/pkg/nodejs/pulumi/eks/

[Sefiris]

+1 to this, i see this has already been open for more than a year, and I would document it myself if i actually understood this, however I've tried using this in combination with KubeconfigOptions.role_arn as to not deploy an EKS cluster through the pulumi iam user but through an IAM role but the runs always end in the kube api requiring credentials