Add a README section on image builds

Author: silverlyra

README.md

@@ -38,7 +38,22 @@ Use the [Helm](https://helm.sh/) chart:
 helm install chart/
 ```
 
-Or user the docker image [maxrocketinternet/k8s-event-logger](https://hub.docker.com/r/maxrocketinternet/k8s-event-logger)
+Or use the docker image [maxrocketinternet/k8s-event-logger][image]
+
+[image]: https://hub.docker.com/r/maxrocketinternet/k8s-event-logger
+
+#### Building a container image
+
+If you're unable to use the [prebuilt][image] docker image, you can build it yourself:
+
+```sh
+make IMG=your.docker.registry/k8s-event-logger image
+```
+
+This uses `docker buildx` to create a [multi-platform image][]. To set up your build host system to be able to build these images, see [this guide][qemu-binfmt].
+
+[multi-platform image]: https://docs.docker.com/build/building/multi-platform/
+[qemu-binfmt]: https://docs.nvidia.com/datacenter/cloud-native/playground/x-arch.html
 
 ### Testing