Update install.md to fully cover creating the necessary IAM role and service account

[pgasca]

/kind bug

What happened?
This procedure points to "Creating the Amazon EBS CSI driver IAM role for service accounts" from the EKS User Guide.. However, that procedure is NOT intended for users who are using the EBS CSI driver as a self-managed addon.

What you expected to happen?
Remove the reference to that procedure and update the install.md file instructions to include details such as creating/annotating the ebs-csi-controller-sa service account.

How to reproduce it (as minimally and precisely as possible)?
https://github.com/kubernetes-sigs/aws-ebs-csi-driver/blob/master/docs/install.md#set-up-driver-permissions

Anything else we need to know?:
The intended scope of the EKS User Guide is to only cover the managed add-on case, so the GitHub repo files need to fully cover how to use the driver as self-managed without referencing the EKS User Guide. This may warrant further changes beyond what I mention.

Environment

• Kubernetes version (use kubectl version):
• Driver version:

[AndrewSirenko]

/assign

[torredil]

/kind documentation