I have set up a kubenetes cluster by kubeadm. Now I want to set up the istio, but I found the istio document did not include the guides about the kubeadm.
It include the instructions for minikube and other cloud provider, how to set up the istio for kubeadm?
These titles in your screenshot, are not instructions for installing Istio on those platforms, they are just Kubernetes installation on different platforms which are prerequisites for Istio installation. If you already have Kubernetes cluster installed (even via kubeadm), just follow Installation Setups for Istio.