Move appendix subsections under appendix section

This involved a small code change to the generated configuration
properties snippets. The section id has to start with
'appendix.', otherwise the section-id asciidoctor extension
complains. To ensure that the anchors that are derived from the
section IDs remain backwards compatible, the anchor-rewrite
properties have been updated.

See gh-29667

Author: mhalbritter

buildSrc/src/main/java/org/springframework/boot/build/context/properties/Snippets.java

@@ -90,7 +90,9 @@ private Set<String> writeSnippet(Path outputDirectory, Snippet snippet, Set<Stri
 
 	private Asciidoc getAsciidoc(Snippet snippet, Table table) {
 		Asciidoc asciidoc = new Asciidoc();
-		asciidoc.appendln("[[" + snippet.getAnchor() + "]]");
+		// We have to prepend 'appendix.' as a section id here, otherwise the
+		// spring-asciidoctor-extensions:section-id asciidoctor extension complains
+		asciidoc.appendln("[[appendix." + snippet.getAnchor() + "]]");
 		asciidoc.appendln("== ", snippet.getTitle());
 		table.write(asciidoc);
 		return asciidoc;

spring-boot-project/spring-boot-docs/src/docs/asciidoc/anchor-rewrite.properties

@@ -1,5 +1,5 @@
 [appendix]
-[[application-properties]]
+[[appendix.application-properties]]
 = Common Application Properties
 include::attributes.adoc[]
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/application-properties.adoc

@@ -1,5 +1,5 @@
 [appendix]
-[[auto-configuration-classes]]
+[[appendix.auto-configuration-classes]]
 = Auto-configuration Classes
 include::attributes.adoc[]
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/auto-configuration-classes.adoc

@@ -1,4 +1,4 @@
-[[auto-configuration-classes.actuator]]
+[[appendix.auto-configuration-classes.actuator]]
 == spring-boot-actuator-autoconfigure
 The following auto-configuration classes are from the `spring-boot-actuator-autoconfigure` module:
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/auto-configuration-classes/actuator.adoc

@@ -1,4 +1,4 @@
-[[auto-configuration-classes.core]]
+[[appendix.auto-configuration-classes.core]]
 == spring-boot-autoconfigure
 The following auto-configuration classes are from the `spring-boot-autoconfigure` module:
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/auto-configuration-classes/core.adoc

@@ -1,7 +1,7 @@
 [[build-tool-plugins.other-build-systems]]
 == Supporting Other Build Systems
 If you want to use a build tool other than Maven, Gradle, or Ant, you likely need to develop your own plugin.
-Executable jars need to follow a specific format and certain entries need to be written in an uncompressed form (see the "`<<executable-jar#executable-jar, executable jar format>>`" section in the appendix for details).
+Executable jars need to follow a specific format and certain entries need to be written in an uncompressed form (see the "`<<executable-jar#appendix.executable-jar, executable jar format>>`" section in the appendix for details).
 
 The Spring Boot Maven and Gradle plugins both make use of `spring-boot-loader-tools` to actually generate jars.
 If you need to, you may use this library directly.

spring-boot-project/spring-boot-docs/src/docs/asciidoc/build-tool-plugins/other-build-systems.adoc

@@ -1,6 +1,6 @@
 [[build-tool-plugins.whats-next]]
 == What to Read Next
 If you are interested in how the build tool plugins work, you can look at the {spring-boot-code}/spring-boot-project/spring-boot-tools[`spring-boot-tools`] module on GitHub.
-More technical details of the executable jar format are covered in <<executable-jar#executable-jar,the appendix>>.
+More technical details of the executable jar format are covered in <<executable-jar#appendix.executable-jar,the appendix>>.
 
 If you have specific build-related questions, you can check out the "`<<howto#howto, how-to>>`" guides.

spring-boot-project/spring-boot-docs/src/docs/asciidoc/build-tool-plugins/whats-next.adoc

@@ -146,7 +146,7 @@ Doing so consults Spring Boot's default dependency metadata to deduce the artifa
 
 NOTE: The default metadata is tied to the version of the CLI that you use.
 It changes only when you move to a new version of the CLI, putting you in control of when the versions of your dependencies may change.
-A table showing the dependencies and their versions that are included in the default metadata can be found in the <<dependency-versions#dependency-versions,appendix>>.
+A table showing the dependencies and their versions that are included in the default metadata can be found in the <<dependency-versions#appendix.dependency-versions,appendix>>.
 
 
 

spring-boot-project/spring-boot-docs/src/docs/asciidoc/cli/using-the-cli.adoc

@@ -1,5 +1,5 @@
 [appendix]
-[[configuration-metadata]]
+[[appendix.configuration-metadata]]
 = Configuration Metadata
 include::attributes.adoc[]
 
@@ -9,7 +9,7 @@ Spring Boot jars include metadata files that provide details of all supported co
 The files are designed to let IDE developers offer contextual help and "`code completion`" as users are working with `application.properties` or `application.yml` files.
 
 The majority of the metadata file is generated automatically at compile time by processing all items annotated with `@ConfigurationProperties`.
-However, it is possible to <<configuration-metadata#configuration-metadata.annotation-processor.adding-additional-metadata,write part of the metadata manually>> for corner cases or more advanced use cases.
+However, it is possible to <<configuration-metadata#appendix.configuration-metadata.annotation-processor.adding-additional-metadata,write part of the metadata manually>> for corner cases or more advanced use cases.