Refactor Asciidoctor attributes in reference docs

This commit reorganizes the asciidoctor attributes for the reference
documentation. Instead of being contributed partially by the build and
individual documents, attributes are now shared in common files that are
included in top sections.

framework-docs/framework-docs.gradle

@@ -80,8 +80,6 @@ rootProject.tasks.dokkaHtmlMultiModule.configure {
 }
 
 asciidoctorj {
-	def docRoot = 'https://docs.spring.io'
-	def docsSpringFramework = "${docRoot}/spring-framework/docs/${project.version}"
 	version = '2.4.3'
 	fatalWarnings ".*"
 	options doctype: 'book', eruby: 'erubis'
@@ -92,11 +90,7 @@ asciidoctorj {
 			revnumber: project.version,
 			sectanchors: '',
 			sectnums: '',
-			'spring-version': project.version,
-			'spring-framework-main-code': 'https://github.com/spring-projects/spring-framework/tree/main',
-			'doc-root': docRoot,
-			'docs-spring-framework': docsSpringFramework,
-			'api-spring-framework': "${docsSpringFramework}/javadoc-api/org/springframework"
+			'spring-version': project.version
 	])
 }