Update documentation on how to use helm charts to setup etcd-druid

[unmarshall]

How to categorize this issue?

/area documentation
/kind enhancement

What would you like to be added:
Add documentation on how to use helm charts for deploying etcd-druid. Include the following:

• How to use helm charts (packaged as OCI artifact) to install etcd-druid.
• How to either use out-of-box support for TLS generation or use an external solution like cert-manager to manage TLS artifacts.
• Add the markdown files as part of mkdocs.yml

Why is this needed: