Add more Kubernetes documentation

Currently we have one section "Containers" for all of it.

But I think there is enough now to make a "Kubernetes" section?

Besides single-node and multi-node, I was also thinking of:

* How to add the new "proxy" and "mirror" parameters, for cache
#5381

* How to install the Kubernetes Dashboard (headlamp) with helm
#5289

Currently the information is a bit scattered in PRs and Discussions.

And to make the k3s/k8s/etc a little less cluttered:

[Containers](https://lima-vm.io/docs/examples/containers/)
* containerd (Default)
* Docker
* Podman
* ~~Kubernetes~~
* Apptainer

[Kubernetes](https://lima-vm.io/docs/examples/containers/kubernetes/)
* Single-node
* Multi-node
* _Cache apt/oci_
* _Dashboard_

Also since it is _also_ using containerd, by default. WDYT?

i.e. the docker and podman were quite short, but kubernetes was long

Trying to add even more information to that page would be too much?

Start with docs/examples/containers/ and the proposed docs/examples/containers/kubernetes/ page, then review the referenced PRs #5381 and #5289 plus related Discussions. Separate Kubernetes material from the Containers section and organize single-node, multi-node, cache parameters, and Dashboard/Helm guidance as appropriate. Done means the Kubernetes content is no longer cluttering the Containers page and the proposed topics are covered.

Written by the indexing model from the issue text.