Use relative links for Javadoc in User Guide (#310)

Author: marcphilipp

build.gradle

@@ -444,9 +444,8 @@ configure(rootProject) {
 		}
 	}
 
-	// docsVersion is also used in documentation.gradle.
-	ext.docsVersion = project.version.contains('SNAPSHOT') ? 'snapshot' : project.version
-	ext.docsDir = new File(buildDir, 'ghpages-docs')
+	def docsVersion = project.version.contains('SNAPSHOT') ? 'snapshot' : project.version
+	def docsDir = new File(buildDir, 'ghpages-docs')
 
 	task prepareDocsForUploadToGhPages(dependsOn: [aggregateJavadocs, ":documentation:asciidoctor"], type: Copy) {
 		outputs.dir docsDir

documentation/documentation.gradle

@@ -37,7 +37,6 @@ asciidoctor {
 	attributes	'jupiter-version': project.property('version'),
 				'platform-version': project.property('platformVersion'),
 				'vintage-version': project.property('vintageVersion'),
-				'docs-version': project.property('docsVersion'),
 				'release-branch': project.property('releaseBranch'),
 				'revnumber' : project.version,
 				'mainDir': project.sourceSets.main.java.srcDirs[0],

documentation/src/docs/asciidoc/index.adoc

@@ -4,8 +4,7 @@ Stefan Bechtold; Sam Brannen; Johannes Link; Matthias Merdes; Marc Philipp
 
 :sectnums:
 
-:docs-root:                         http://junit.org/junit5/docs/{docs-version}
-:javadoc-root:                      {docs-root}/api
+:javadoc-root:                      link:../api
 
 :snapshot-repo:                     https://oss.sonatype.org/content/repositories/snapshots