build_osx.md is out of date

[cgwalters]

Issue Description

It seems like for podman5 we take a dependency on fetching a disk image from a registry, and this requires us to have at least containers.conf installed.

#21862 is relevant but earlier PRs are too.

Can someone who knows this please update the build_osx.md with what steps need to be done here?

Steps to reproduce the issue

Try to use build_osx.md

Describe the results you received

> podman machine init --now --rootful -m 8192
Error: failed to pull quay.io/baude/stage-podman-machine-image@sha256:a1214cf6fccc9f8de03af65c6b65439d022e3a4c1ff8d161ed606921449dd871: no DefaultPolicyJSONPath defined and no local overwrites found: ["stat /Users/walters/.config/containers/policy.json: no such file or directory" "stat /etc/containers/policy.json: no such file or directory"]

Describe the results you expected

Functioning podman-machine

podman info output

$ podman --version
podman version 5.0.0-dev
$ git rev-parse HEAD
413819de0747b74219ec68f5a61e241886d10387
$

### Podman in a container

No

### Privileged Or Rootless

Rootless

### Upstream Latest Release

Yes

### Additional environment details

Additional environment details

### Additional information

_No response_

[Luap99]

see also #21855

[cgwalters]

Thanks; yeah this is basically a duplicate..