Fixes an HNS network by adding a HostRoute policy to one that was created without it. A workaround for if you're running Flannel 0.11.0 and therefore
missing the patch from flannel-io/flannel#1096
curl.exe -LO https://github.com/benmoss/fix-houstroute-policy/releases/latest/download/fix-hostroute-policy.exe
./fix-hostroute-policy.exe vxlan0
The argument is just your HNS Network name, which if you're using the https://github.com/kubernetes-sigs/sig-windows-tools/tree/master/kubeadm/ script will be vxlan0.