'dnf install' and rpm does this on ostree/bootc (and in general, image based systems):

error: can't create transaction lock on /usr/share/rpm/.rpm.lock (Read-only file system)

This happens to only be the first error; beyond that on an image-based system the `/usr` filesystem is read-only by default.

Instead, we should land code in dnf (and ideally, rpm) that: gives an improved error message that redirects users to a canonical documentation page that we will keep up to date.

For example, on RHEL:

```
$ dnf -y install strace
error: system is configured to be read-only; for more information see https://docs.redhat.com/en/documentation/red_hat_enterprise_linux/9/html/managing_software_with_the_dnf_tool/assembly_image_mode
```

Yes I'm proposing this links directly to the "managing software with dnf" section of the RHEL docs; and part of the deliverable here is we provide useful information there, with best practices and recommendations.

(The documentation of course gets into a larger problem that docs aren't generally shared between fedora and RHEL, and we should do something useful on Fedora too, that could link to something underneath https://docs.fedoraproject.org/en-US/bootc/ perhaps there, as a build-time config)