Fixed broken iframe link.

src/docs/asciidoc/jme3/scenegraph_for_dummies.adoc

@@ -10,15 +10,16 @@ ifdef::env-github,env-browser[:outfilesuffix: .adoc]
 
 == jMonkeyEngine3 Scene Graph for Dummies
 
-iframe::https://jmonkeyengine.github.io/wiki/tutorials/scenegraph[width="100%", height="850px", alt="", scroll="true",border="true",align="false"]
+++++
+<iframe src=https://jmonkeyengine.github.io/wiki/tutorials/scenegraph width="100%" height="850px" alt=""></iframe>
+++++
+//iframe::https://jmonkeyengine.github.io/wiki/tutorials/scenegraph[width="100%", height="850px", alt="", scroll="true",border="true",align="false"]
 
 
 [TIP]
 ====
 
-
 *  You can open this presentation in link:https://jmonkeyengine.github.io/wiki/tutorials/scenegraph[Fullscreen Mode].
 *  When using link:http://www.apple.com/safari/[Safari] as a browser the presentation is animated.
 
-
 ====