fix links

docs/modules/tutorials/pages/concepts/faq.adoc

@@ -117,8 +117,7 @@ rootNode.detachChild(spatial); // remove from scene
 
 *Learn more:*
 
-* xref:concepts
-  /the_scene_graph.adoc[The Scene Graph]
+* xref:concepts/the_scene_graph.adoc[The Scene Graph]
 * xref:beginner/hello_node.adoc[Hello Node]
 * xref:beginner/hello_asset.adoc[Hello Asset]
 * xref:ROOT:jme3/advanced/spatial.adoc[Spatial]