Move configuration property sections from buildSrc to spring-boot-docs

[snowykte0426]

Description

This pull request addresses issue #23972 by moving the configuration of property sections from the buildSrc module to the spring-boot-docs module's build.gradle script.

Problem

The configuration property sections for the appendix were hardcoded in the DocumentConfigurationProperties task within the buildSrc module. This approach had a significant drawback: whenever changes were made to these sections, it would trigger a complete rebuild of the entire project due to how Gradle treats changes in the buildSrc directory.

Solution

This PR refactors the approach by:

1. Modifying DocumentConfigurationProperties class: Added support for declarative configuration through a new ListProperty<PropertySectionDefinition> field that allows external configuration of property sections.

2. Creating PropertySectionDefinition class: A new data class that encapsulates section information including filename, title, prefixes, and descriptions.

3. Moving configuration to spring-boot-docs/build.gradle: The property sections are now declaratively configured in the documentConfigurationProperties task within the docs module's build script.

Benefits

• Improved build performance: Changes to property sections no longer trigger full project rebuilds
• Better maintainability: Configuration is now declarative and easier to modify
• Clearer separation of concerns: Build logic stays in buildSrc while configuration moves to the appropriate module

Changes Made

• Modified buildSrc/src/main/java/org/springframework/boot/build/context/properties/DocumentConfigurationProperties.java to support external configuration
• Updated documentation/spring-boot-docs/build.gradle to include declarative property section definitions

The implementation maintains backward compatibility by providing default sections when no external configuration is specified.

[wilkinsona]

Thanks for the PR. Please sign your commits as described in the DCO check failure.

[snowykte0426]

Thanks for the PR. Please sign your commits as described in the DCO check failure.

Hi @wilkinsona,
Thank you for the feedback. I apologize for the missing DCO sign-off on the commits.
The DCO issue occurred while I was resolving merge conflicts - I accidentally made commits without proper sign-off during the conflict resolution process.
Should I resolve this immediately?

Please let me know if you'd like me to handle this right away or if there's a preferred timing for the fix.