Added a note about a k3s issue wrt iptables

Signed-off-by: Eduardo Minguez <[email protected]>

README.md

@@ -291,3 +291,7 @@ Related tools:
 * [kind](https://github.com/kubernetes-sigs/kind) - kind can run a Kubernetes cluster within a Docker container for local development. k3s is also suitable for this purpose through `k3d`. KinD is not suitable for running a remote cluster for development.
 * [kubeadm](https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/create-cluster-kubeadm/) - a tool to create fully-loaded, production-ready Kubernetes clusters with or without high-availability (HA). Tends to be heavier-weight and slower than k3s. It is aimed at cloud VMs or bare-metal computers which means it doesn't always work well with low-powered ARM devices.
 * [k3v](https://github.com/ibuildthecloud/k3v) - "virtual kubernetes" - a very early PoC from the author of k3s aiming to slice up a single cluster for multiple tenants
+
+## Appendix
+
+* Currently there is an issue in k3s involving `iptables >= 1.8` that can affect the network communication. See the [k3s issue](https://github.com/rancher/k3s/issues/703) and the corresponding [kubernetes one](https://github.com/kubernetes/kubernetes/issues/71305) for more information and workarounds. The issue has been observed in Debian Buster but it can affect other distributions as well.