Various documentation updates (#8243)

* 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* Docs: clean up outdated roadmap and point to github issues instead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

docs/roadmap.md

@@ -1,62 +1,3 @@
 # Kubespray's roadmap
 
-## Self deployment (pull-mode) [#320](https://github.com/kubespray/kubespray/issues/320)
-
-- the playbook would install and configure docker and the etcd cluster
-- the following data would be inserted into etcd: certs,tokens,users,inventory,group_vars.
-- a "kubespray" container would be deployed (kubespray-cli, ansible-playbook)
-- to be discussed, a way to provide the inventory
-- **self deployment** of the node from inside a container [#321](https://github.com/kubespray/kubespray/issues/321)
-
-## Provisioning and cloud providers
-
-- [ ] Terraform to provision instances on:
-  - [ ] GCE
-  - [x] AWS (contrib/terraform/aws)
-  - [x] OpenStack (contrib/terraform/openstack)
-  - [x] Equinix Metal
-  - [ ] Digital Ocean
-  - [ ] Azure
-- [ ] On AWS autoscaling, multi AZ
-- [ ] On Azure autoscaling, create loadbalancer [#297](https://github.com/kubespray/kubespray/issues/297)
-- [ ] On GCE be able to create a loadbalancer automatically (IAM ?) [#280](https://github.com/kubespray/kubespray/issues/280)
-- [x] **TLS bootstrap** support for kubelet (covered by kubeadm, but not in standard deployment) [#234](https://github.com/kubespray/kubespray/issues/234)
-  (related issues: <https://github.com/kubernetes/kubernetes/pull/20439> <https://github.com/kubernetes/kubernetes/issues/18112)>
-
-## Tests
-
-- [x] Run kubernetes e2e tests
-- [ ] Test idempotency on single OS but for all network plugins/container engines
-- [ ] single test on AWS per day
-- [ ] test scale up cluster:  +1 etcd, +1 control plane, +1 node
-- [x] Reorganize CI test vars into group var files
-
-## Lifecycle
-
-- [ ] Upgrade granularity: select components to upgrade and skip others
-
-## Networking
-
-- [ ] Opencontrail
-- [ ] Consolidate roles/network_plugin and roles/kubernetes-apps/network_plugin
-
-## Kubespray API
-
-- Perform all actions through an **API**
-- Store inventories / configurations of multiple clusters
-- Make sure that state of cluster is completely saved in no more than one config file beyond hosts inventory
-
-## Addons (helm or native ansible)
-
-- [x] Helm
-- [x] Ingress-nginx
-- [x] kubernetes-dashboard
-
-## Others
-
-- Organize and update documentation (split in categories)
-- Refactor downloads so it all runs in the beginning of deployment
-- Make bootstrapping OS more consistent
-- **consul** -> if officially supported by k8s
-- Flex volumes options (e.g. **torrus** support) [#312](https://github.com/kubespray/kubespray/issues/312)
-- Clusters federation option (aka **ubernetes**) [#329](https://github.com/kubespray/kubespray/issues/329)
+We are tracking the evolution towards Kubespray 3.0 in [#6400](https://github.com/kubernetes-sigs/kubespray/issues/6400) as well as in other open issue in our [github issues](https://github.com/kubernetes-sigs/kubespray/issues/) section.