Update variable elimination web app link with archived version

inference/ve/index.md

@@ -100,7 +100,7 @@ More formally, for each variable $$X_i$$ (ordered according to $$O$$),
 2. Marginalize out $$X_i$$ to obtain a new factor $$\tau$$
 3. Replace the factors $$\Phi_i$$ with $$\tau$$
 
-A former CS228 student has created an [interactive web simulation](http://pgmlearning.herokuapp.com/vElimApp) for visualizing the variable elimination algorithm. Feel free to play around with it and, if you do, please submit any feedback or bugs through the Feedback button on the web app.
+A former CS228 student has created an [interactive web simulation](https://web.archive.org/web/20221024031253/https://pgmlearning.herokuapp.com/vElimApp) for visualizing the variable elimination algorithm. Feel free to play around with it and, if you do, please submit any feedback or bugs through the Feedback button on the web app.
 
 ### Examples