Quarkus: Document how to create a multi-module Maven project

[gsmet]

Now that we have support for multi-modules Maven project, we should properly document them:

• the empty beans.xml trick;
• using quarkus:dev in a multi-module environment

[ktulinho]

Any updates on this? I was trying to get multi module to work on my test project but I haven't been able to make it work yet

[wjglerum]

Last week I was facing the same problem. With the info I found scattered over Github and Zulip I could make it work. Created PR's for this issue to help others with this problem. Feedback highly appreciated :)

[wjglerum]

@gsmet I provided a pr with the docs and a quickstart example, see https://github.com/quarkusio/quarkus/pull/9164 and https://github.com/quarkusio/quarkus-quickstarts/pull/559/files

Any thoughts or feedback?