Include additional folder for the container volume mounts in `dind-rootless` variant

I have a k8s pod consisted of an app container and a dind container and want to share the dind volumes to the app container. It would be nice to create a folder in the dind-rootless image for that (/home/rootless/data perhaps? /home/rootless/volumes?).

As of now, I need to build another image from dind-rootless to make permissions work across images since there is no way to set up permissions during the volume mount (I'm using a non-root user on the app container as well):

FROM docker:19.03.11-dind-rootless

RUN mkdir -p /home/rootless/volumes \
  && chown -R rootless /home/rootless/volumes

Not a huge deal, however, it seems like a common use-case and perhaps it's reasonable to include in the dind-rootless image itself.

Start by locating the Dockerfile or build entry point for the dind-rootless variant and compare it with the shown Dockerfile. Confirm the intended mount directory and verify that the built image contains it with ownership suitable for the rootless user; the image build should complete successfully.