Adding content for public helm repo

[dlakhaws]

Description of changes:

• Adding content for public helm repo
• Will test after this is merged by doing

helm repo add aws-s3-csi-driver https://awslabs.github.io/mountpoint-s3-csi-driver

• if this works, will add these steps to release runbook:

Package the new release for helm: `helm package charts/aws-s3-csi-driver`
Update the index.yaml: `helm repo index --url https://github.com/awslabs/mountpoint-s3-csi-driver .`

[jjkr]

Is checking in this tarball temporary to test out your changes? I'd imagine we'd want to pull any artifacts from CI.

[dlakhaws]

from my research, the tarball is necessary for public helm repos, the other drivers don't need to do it because they are in the kubernetes-sigs group that seems to do something behind the scenes on packaging the drivers