Review doc generation logic

[flazarus1A]

I had to remove the doc -> deployment dependency here, because generate-resources does not package artifacts, and it is used to prepare the doc for releasing.
As a consequence, the goal fails on the impl module, that needs its dependencies to proceed further.

The first releases went through with a similar project structure, so I assume the release job relies on cached SNAPSHOT artifacts for this step, that were somehow missing today.

quarkus-cxf maintainers chose to go for install in the release goal, but it's the only other extension I've found to use that trick.
In this repository, we chose to simply isolate docs, since we don't rely on resource imports anyway.

To be checked if this is a side effect of some other problem.