Fix missing reference doc from docs archive

Prior to this commit, the `docsZip` task would not reference the new
output locations for the `asciidoctor` and `asciidoctorPdf` tasks.
This results with missing reference docs in the docs zip.

This commit updates the input locations of the Zip task to include the
produced reference docs.

Fixes gh-25783

gradle/docs.gradle

@@ -153,7 +153,6 @@ asciidoctorj {
  * in "build/docs/ref-docs/html5".
  */
 asciidoctor {
-	dependsOn asciidoctorPdf
 	baseDirFollowsSourceDir()
 	configurations 'asciidoctorExt'
 	sources {
@@ -186,7 +185,7 @@ asciidoctorPdf {
 /**
  * Zip all docs (API and reference) into a single archive
  */
-task docsZip(type: Zip, dependsOn: ['api', 'asciidoctor', 'dokka']) {
+task docsZip(type: Zip, dependsOn: ['api', 'asciidoctor', 'asciidoctorPdf', 'dokka']) {
 	group = "Distribution"
 	description = "Builds -${archiveClassifier} archive containing api and reference " +
 			"for deployment at https://docs.spring.io/spring-framework/docs."
@@ -199,10 +198,10 @@ task docsZip(type: Zip, dependsOn: ['api', 'asciidoctor', 'dokka']) {
 	from (api) {
 		into "javadoc-api"
 	}
-	from ("$asciidoctor.outputDir/html5") {
+	from ("$asciidoctor.outputDir") {
 		into "spring-framework-reference"
 	}
-	from ("$asciidoctor.outputDir/pdf") {
+	from ("$asciidoctorPdf.outputDir") {
 		into "spring-framework-reference/pdf"
 	}
 	from (dokka) {