fix: ddsim -> npsim

Author: wdconinc

_documentation/links.md

@@ -11,7 +11,7 @@ layout: default
 #### ePIC Tutorial 1
 1. [Setting up an enviroment](https://eic.github.io/tutorial-setting-up-environment/)
 1. [Geometry within dd4hep](https://eic.github.io/tutorial-geometry-development-using-dd4hep/ )
-1. [Simulation with ePIC singularity container](https://eic.github.io/tutorial-simulations-using-ddsim-and-geant4/)
+1. [Simulation with ePIC singularity container](https://eic.github.io/tutorial-simulations-using-npsim-and-geant4/)
 1. [Reconstruction framework](https://eic.github.io/tutorial-jana2/)
 
 #### ePIC Tutorial 2