Providing default docker image with custom built AMI

**Platform I'm building on:**
Linux 5.8.9-arch2-1 GNU/Linux

**What I expected to happen:**
Find information on how to provide a default image to package with Bottlerocket OS when doing a custom build

I would like to be able to include a default image with the Bottlerocket OS so that upon starting the OS, and subsequently trying to start a docker container, I would not have to wait for the image being pulled, as is customary in e.g. Fargate tasks (see https://github.com/aws/containers-roadmap/issues/358)

**What actually happened:**
Found information on how to build a custom Bottlerocket OS in https://github.com/bottlerocket-os/bottlerocket/blob/develop/BUILDING.md but not information on how to provide a default docker image

**How to reproduce the problem:**
N/A