Added raspberry pi-related notes to the knowledge base

knowledge base/raspberry pi os.md

@@ -0,0 +1,34 @@
+# Raspberry Pi OS
+
+## Let it run containers
+
+### Kernel containerization features
+
+Enable containerization features in the kernel to be able to run containers as intended.
+
+Add the following properties at the end of the line in `/boot/cmdline.txt`:
+
+```shell
+cgroup_enable=cpuset cgroup_memory=1 cgroup_enable=memory
+```
+
+### Firewall settings
+
+Switch Debian firewall to legacy config:
+
+```shell
+update-alternatives --set iptables  /usr/sbin/iptables-legacy
+update-alternatives --set ip6tables /usr/sbin/ip6tables-legacy
+```
+
+## Sources
+
+- The [k3s] project page
+- The [Build your very own self-hosting platform with Raspberry Pi and Kubernetes] series of articles
+- [Run Kubernetes on a Raspberry Pi with k3s]
+- Project's [issue 2067]
+
+[build your very own self-hosting platform with raspberry pi and kubernetes]: https://kauri.io/build-your-very-own-self-hosting-platform-with-raspberry-pi-and-kubernetes/5e1c3fdc1add0d0001dff534/c
+[issue 2067]: https://github.com/k3s-io/k3s/issues/2067#issuecomment-664052806
+[k3s]: https://k3s.io/
+[run kubernetes on a raspberry pi with k3s]: https://opensource.com/article/20/3/kubernetes-raspberry-pi-k3s