* Add kubeadm option to etcd_deployment_type to replace the etcd_kubeadm_enabled variable

Signed-off-by: necatican <necaticanyildirim@gmail.com>

* Add etcd kubeadm deployment documentation

Signed-off-by: necatican <necaticanyildirim@gmail.com>

* Refactor warning for the deprecated 'etcd_kubeadm_enabled' variable

Signed-off-by: necatican <necaticanyildirim@gmail.com>