diff --git a/poc-datacollector/modules/ROOT/pages/doc-dummy_service.adoc b/poc-datacollector/modules/ROOT/pages/doc-dummy_service.adoc
index 94fb708..228bfea 100644
--- a/poc-datacollector/modules/ROOT/pages/doc-dummy_service.adoc
+++ b/poc-datacollector/modules/ROOT/pages/doc-dummy_service.adoc
@@ -10,7 +10,7 @@
 
 == edit
 
-[source,ruby,linenums]
+[source,ruby,highlight=6..18]
 ----
 <match debug.*>
   @type stdout