Improve Spring Framework Artifacts wiki page

[sbrannen]

The Spring Framework Artifacts wiki page currently only provides examples of configuring the version for spring-context which can lead to confusion for some users who are unfamiliar with dependency management.

We should therefore clarify that the spring-context examples are meant to demonstrate how to configure the version for a single Spring Framework artifact.

We should also provide guidance for upgrading the Spring Framework version for Spring Boot users.

[sbrannen]

Completed in commit:

https://github.com/spring-projects/spring-framework/wiki/Spring-Framework-Artifacts/_compare/8ea7f1d220f2a7df89e8ac449f59e2d875da2143...790c10392ff19db7f3678bcfa580c4f5e50c6b87

Improve Spring Framework Artifacts wiki page

Prior to this commit, the Spring Framework Artifacts wiki page only
provided examples of configuring the version for spring-context which
lead to confusion for users who are unfamiliar with dependency
management.

This commit therefore revises the wiki page as follows.

• Clarify that the spring-context examples are meant to demonstrate how
  to configure the version for a single Spring Framework artifact.

• Split repository and dependency configuration examples.

• Provide guidance for upgrading the Spring Framework version for
  Spring Boot users.

Closes #34002