Fix guides spec

docs/guides/build.gradle

@@ -1,9 +1,6 @@
+apply plugin: 'asciidoctor'
 
-import org.asciidoctor.gradle.*
-
-file("src/asciidoc").eachFileMatch(~/.*\.asc/) { file->
-    task "asciidoctor-${file.name}"(type: AsciidoctorTask) {
-        sourceDocumentName = file
+asciidoctor {
     options = [
       eruby: 'erubis',
       eruby: 'erubis',
@@ -21,16 +18,10 @@ file("src/asciidoc").eachFileMatch(~/.*\.asc/) { file->
       ]
     ]
 }
-}
-
-task asciidoctor {
-    group = 'Documentation'
-    description = "Generates the asciidoc for $project.name"
-    dependsOn tasks.matching { t -> t.name.startsWith('asciidoctor-') }
-}
 
 ext.spec = copySpec {
     into ('guides') {
-        from("$buildDir/asciidoctor/dist/html5/")
+        from(asciidoctor.outputDir)
+        exclude 'build', 'Guardfile'
     }
 }