Clarify Use Docker with Minikube documentation

[MarkvanMents]

The current documentation gives an example of using Docker with Minikube. This is intended as a proof of concept explanation rather than a full-blown explanation of using Mendix on Kubernetes. However it appears above Mendix for Private Cloud, the fully supported offering for deploying to Kubernetes, in Google searches such as Mendix Kubernetes.

This PR highlights the use case for deploying on Minikube and clarifies the limitations compared to Mendix for Private Cloud.

Publishing this will not immediately update Google search - we should force Google to re-index this manually so that we can review the impact on search results.