Update documentation for running in a container (#11052)
This PR rewords the instructions for using uv in a container. I'm a new
user and was somewhat confused by it, so I've rewritten it as I'd have
liked to have read it.
It makes it more clear what distroless means, to avoid confusion with
other projects that ship OS files with an image with its tag name clear
of qualifiers(`astral-sh/uv`, in this case). An example of that is
caddy, which ships with alpine.
This also modifies the original example to use a distroful image instead
of distroless one while #8635 doesn't get resolved.
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Co-authored-by: Zanie Blue <contact@zanie.dev>
