Add details about relocations into README and/or CONTRIBUTING

[rsvoboda]

Description

I don't see in Quarkus README or CONTRIBUTING documents any suggestion to use relocations profile.

This can be handy for people working with Quarkus main. Especially after #38190 change and with the upcoming https://github.com/quarkusio/quarkus/blob/main/adr/0002-reactive-rename.adoc changes.

CI is building Quarkus main with relocations:

• https://github.com/quarkus-qe/quarkus-test-suite/blob/main/.github/workflows/ci.yml#L25
• https://github.com/quarkus-qe/quarkus-test-suite/blob/main/.github/workflows/daily.yaml#L27

CC @gsmet @geoand

Implementation ideas

No response

[geoand]

I am not exactly sure what you would like to have documented around this. Who do you envision will be helped by such documentation and how?

[rsvoboda]

Building with relocations section in https://github.com/quarkusio/quarkus/blob/main/CONTRIBUTING.md#workflow-tips

[maxandersen]

same question as @geoand - not following what the usecase is? isn't that profile not only to use when publishing - and not needed elsewhere?

[rsvoboda]

I created #38341 to show my idea.

This is the main trigger: quarkus-qe/quarkus-test-suite#1617 (comment)
We are working on test development in main branch of qe test-suite and we backport bulks to 3.2 / 2.13 branch.
Thus we want to keep main branch compatible with 3.2 as much as possible (at least till 3.8 is out).

[maxandersen]

had a quick chat with @gsmet and the reason we do not enable by default is to make sure its noticed by extension writers or users that the artifact names are changing. If we enable by default these issues would not be noticed until its too late.

Those (like QE) that want to maintain a build that works on both branches should enable the -Drelocation knowing that its fine to do so but they might at least from time to time test withuot relocations to detect possible issues.

[michalvavrik]

Makes sense, thanks for the context.

[rsvoboda]

@maxandersen ok, so it's intentionally hidden and this should be closed (together with my PR)?