Update index.html

Author: JoseRamosMendez

index.html

@@ -42,7 +42,7 @@ <h3>What is OpenTOPAS ?</h3>
             to provide an easier-to-use application for the medical physicist. 
             OpenTOPAS’s unique parameter control system lets you assemble and control a rich library of simulation objects (geometry components, 
             particle sources, scorers, etc.) with no need to write C++ code and without knowledge of the underlying Geant4 Simulation Toolkit. 
-            Please visit our <a href="https://opentopas.readthedocs.io/en/latest/" target="_blank">User guide</a> for mode details.
+            Please visit our <a href="https://ucsf.box.com/s/5g6n6uvi8goljpsku3z4gi6on959w4n3" target="_blank">User guide</a> for mode details.
             <br> <br>
             OpenTOPAS basic concepts were originally created out of an NIH-funded collaboration of Massachusetts General Hospital, University 
             of California San Francisco, and SLAC National Accelerator Laboratory for the development of the TOPAS software. The current collaboration