Support cert-manager for automatic management of TLS artifacts required to setup etcd-druid

[unmarshall]

How to categorize this issue?

/area open-source
/area dev-productivity
/area documentation
/kind enhancement

What would you like to be added:

• Test cert-manager with etcd-druid and ensure that it can be used to manage TLS artifacts with etcd-druid.
• Ensure that sufficient documentation is provided to support cert-manager.

Why is this needed:
cert-manager is a popular k8s native TLS management solution. It should be possible to use cert-manager to help generate, inject and rotate TLS artifacts required for setting up etcd-druid.