fix comment

docs/modules/tutorials/pages/beginner/hello_node.adoc

@@ -242,7 +242,7 @@ a| Create a Mesh shape, wrap it into a Geometry, and give it a Material. +
 For example:
 [source,java]
 ----
-// a cuboid default mesh
+/** a cuboid default mesh */
 Box mesh = new Box(Vector3f.ZERO, 1, 1, 1);
 Geometry thing = new Geometry("thing", mesh);
 Material mat = new Material(assetManager,