fix link

docs/modules/ROOT/pages/jme3/advanced/jme3_ai.adoc

@@ -834,7 +834,7 @@ There are other jME3 specific options available you can read about in the wiki u
 
 == Further Reading
 
-*  link:http://www.policyalmanac.org/games/aStarTutorial.htm[A* path-finding for Beginners] by Patrick Lester
+*  link:{attachmentsdir}/Astar.pdf[A* path-finding for Beginners] by Patrick Lester
 *  link:http://natureofcode.com/book/[The Nature of Code] by Daniel Shiffman
 *  link:http://www.red3d.com/cwr/steer/gdc99/[Steering Behaviors For Autonomous Characters] by Craig W. Reynolds
 *  link:http://www.critterai.org/projects/nmgen_study/[Study: Navigation Mesh Generation Java] by Stephen Pratt