* Docs: update CONTRIBUTING.md
* Docs: clean up outdated roadmap and point to github issues instead
* Docs: update note on kubelet_cgroup_driver
* Docs: update kata containers docs with note about cgroup driver
* Docs: note about CI specific overrides
* rename ansible groups to use _ instead of -
k8s-cluster -> k8s_cluster
k8s-node -> k8s_node
calico-rr -> calico_rr
no-floating -> no_floating
Note: kube-node,k8s-cluster groups in upgrade CI
need clean-up after v2.16 is tagged
* ensure old groups are mapped to the new ones
* Install Kata Containers as additional container runtime
* Create RuntimeClasses for Kata Containers
* Updated Vagrant to optionally run without Docker as container manager
* Updated Vagrant to optionally use Libvirt nested virtualization
* Add Kata Containers documentation
* Fix lint errors
* Add kata_containers_enabled to kubespray-defaults
* Fixed typo error
* Fixed typo error
Cristian Calin
zhangshj-inspur
Pasquale Toscano