Document the Kubernetes cluster api, how to use it and why it could be interesting

[cmoulliard]

Todo

Document what is the Kubernetes Cluster API project - https://cluster-api.sigs.k8s.io/introduction.html and how to use it.

NOTE: As it supports to create clusters according to different providers, this project could help us to simplify how we provision k8s on Hetzner, IBMCloud and OpenStack.

Cluster API is a Kubernetes sub-project focused on providing declarative APIs and tooling to simplify provisioning, upgrading, and operating multiple Kubernetes clusters.

Started by the Kubernetes Special Interest Group (SIG) Cluster Lifecycle, the Cluster API project uses Kubernetes-style APIs and patterns to automate cluster lifecycle management for platform operators. The supporting infrastructure, like virtual machines, networks, load balancers, and VPCs, as well as the Kubernetes cluster configuration are all defined in the same way that application developers operate deploying and managing their workloads. This enables consistent and repeatable cluster deployments across a wide variety of infrastructure environments.