Refactor configuration code samples to be more relevant for modern Spring applications

[spring-projects-issues]

Current Spring Framework reference documentation can be challenging to use for people developing modern Spring Boot applications. To make it easier, this issue goal is to refactor the documentation in order to provide configuration snippets with tabs for Java, Kotlin and XML in order to avoid being exposed to XML configuration by default (except in dedicated sections).

[spring-projects-issues]

Sébastien Deleuze commented

We can also probably update this kind of statement since usage and best practices have evolved.

[sdeleuze]

I have not the bandwidth to do that for Spring Framework 5.2, but that's probably a good candidate for Spring Framework 5.3.