DATAREDIS-361 - Read html resources for docs zip from asciidoctor output dir.

We now read generated html resources along with required css files from the asciidoctor output directory.

build.gradle

@@ -212,7 +212,7 @@ task docsZip(type: Zip, dependsOn:['asciidoctor', 'referencePdf' ]) {
         into 'api'
     }
 
-    from ("$buildDir/reference/html") {
+    from ("$asciidoctor.outputDir") {
         include "index.html"
         include "spring.css"
         into 'reference/html'