Add packaging example for Picocli documentation

[newur]

I was initially a bit lost how to turn the example into something actually runnable on the cmd. The native executable works fine, but might not be suitable in all cases. So I added an example with an uber-jar and combined it with a maven plugin as described in the official Picocli docu.

[gsmet]

Thanks for your work on this. I added a couple of comments on the form.

[gsmet]

I'm not sure I would put this section here. It is very specific. I would rather keep the existing structure and add a Packaging hints paragraph later.

[newur]

I would like to disagree on this one. So far the article has basically not much structure, since all headlines are on the same level. I want to make it more similar to the other guides and provide a structure with a basic example that covers the happy path or 80% case or whatever one might wanna call it. Afterwards, more advanced solutions are outlined.

Having 3 different ways to implement the entry points, is not something a first time reader can/wants to deal with IMHO. On the other hand, how to get this code running from the command line, is something the reader most likely is interested in.

[newur]

What do we need to do, to get some progress here?

[gsmet]

I made some further adjustments. Let's wait for CI and merge.

[gsmet]

Rebased to get a CI fix.

[github-actions]

🙈 The PR is closed and the preview is expired.

[quarkus-bot]

Status for workflow Quarkus Documentation CI

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It should be safe to merge provided you have a look at the other checks in the summary.