update comment with valid options for bootstrap_os
update comment with valid options for bootstrap_os

Abdelsalam-Abbas/kubespray_fork,Atoms/kubespray,galthaus/setup-kubernetes,insequent/kargo,ayaz/kubespray,VincentS/kargo,Atoms/kubespray,kubernetes-sigs/kubespray,galthaus/setup-kubernetes,sgm-media/kargo,insequent/kargo,Abdelsalam-Abbas/kubespray_fork,Lendico/kargo,Lendico/kargo,ayaz/kubespray,kubernetes-sigs/kubespray,hatch-k8s/kargo,VincentS/kargo,sgm-media/kargo,kubespray/kargo,rogerwelin/kargo,Atoms/kubespray,rogerwelin/kargo,kubespray/kargo,kubernetes-incubator/kubespray,kubernetes-incubator/kubespray,kubernetes-incubator/kargo,kubernetes-sigs/kubespray,kubernetes-incubator/kargo,Atoms/kubespray,kubernetes-sigs/kubespray,hatch-k8s/kargo