Revise "Use Liquibase for test-only migrations" section in reference manual

[vpavic]

Closes gh-39539

[snicoll]

While I agree that it is a good idea to link to official materials rather than explaining third-party features in our own doc, I find the change a bit rough. If you understand liquibase, as well as how to use it in Spring Boot, then you can patch things up and understand how to use it.

However, for a newcomer, you need to map what's described in the liquibase doc to what you'd do in a Spring Boot app (if you wish to). Have you considered keeping the SB-related bits as short as possible and then refer to the doc + blog posts?

[vpavic]

If you understand liquibase, as well as how to use it in Spring Boot...

I would expect this to be the case, because if you're seeking guidance about test-only migrations using a specific library for DB migration, it means you already know how to use it in Spring Boot?

But I do understand that this PR replaces a lot of something with some fairly minimal content consisting of external references. I'll take a look tomorrow into what would be a minimal example of connecting the dots between those external references and something that would be a domain of Spring Boot based application.

[snicoll]

it means you already know how to use it in Spring Boot?

I suppose so but assumptions like that are a bad idea. We need to strike a good balance between repeating ourselves and guiding users to link external content and how it can be used by the project.

a minimal example of connecting the dots between those external references and something that would be a domain of Spring Boot based application.

That's exactly what I am asking, so thanks for that!

[vpavic]

I've added something that should qualify as a minimal example of connecting the dots between those external references and something that would be a domain of Spring Boot based application.

[snicoll]

Thanks @vpavic.