Doc: Kubernetes deployments

[olivercodes]

Kubernetes support was added, via helm chart, here #981

After discussing with @camcash17 - it would be a great help to update the documentation https://www.cloudcarbonfootprint.org/docs/deploying to include deploying to Kubernetes.

Given the chart was added 2 years ago, we'll probably also want to review it for any necessary updates prior to certifying it as a production ready deployment target.

[lukibahr]

I'm currently reviewing it (due to testing it in a hardened environment). Will give an update on my insights and helm chart soon.