Update uid/gid mapping in rootless user case for buildah images.

[TomSweeneyRedHat]

There's a lack of documentation for running the buildahimages on quay.io when running as a rootless user. Add docs to clarify what's needed. More information in #3053 and specifically from @aaabdallah #3053 (comment)

Description

Steps to reproduce the issue:
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Describe the results you received:

Describe the results you expected:

Output of rpm -q buildah or apt list buildah:

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Output of buildah version:

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Output of podman version if reporting a podman build issue:

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Output of cat /etc/*release:

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Output of uname -a:

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Output of cat /etc/containers/storage.conf:

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[github-actions]

A friendly reminder that this issue had no activity for 30 days.

[rhatdan]

@TomSweeneyRedHat Any chance you can tackle this?

[github-actions]

A friendly reminder that this issue had no activity for 30 days.