* add pre-commit hook configuration

* add tmp.md to .gitignore

* describe the use of pre-commit hook in CONTRIBUTING.md

* fix docs/integration.md errors identified by markdownlint

* fix docs/<file>.md errors identified by markdownlint

* docs/azure-csi.md
* docs/azure.md
* docs/bootstrap-os.md
* docs/calico.md
* docs/debian.md
* docs/fcos.md
* docs/vagrant.md
* docs/gcp-lb.md
* docs/kubernetes-apps/registry.md
* docs/setting-up-your-first-cluster.md
* docs/vagrant.md
* docs/vars.md

* fix contrib/<file>.md errors identified by markdownlint

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* Docs: clean up outdated roadmap and point to github issues instead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

tests/scripts/ansible-lint.sh was written on the doc, but there was
not such file actually. We can use ansible-lint command to check
ansible yml files without any options.
This updates to use the command.