fix link

docs/modules/core/pages/gui/loading_screen.adoc

@@ -364,7 +364,7 @@ NOTE: Try and add all controls near the end, as their update loops may begin exe
 
 === Using multithreading
 
-For more info on multithreading: xref:jme3/advanced/multithreading.adoc[The jME3 Threading Model]
+For more info on multithreading: xref:app/multithreading.adoc[The jME3 Threading Model]
 
 Make sure to change the XML file to point the controller to TestLoadingScreen*1*.