Resolve "Explain various benchmarks repositories"

Closes #4 (closed)

src/docs/index.mdx

@@ -19,6 +19,8 @@ together to get some results and serve as a jumping off point for further develo
 
 - [Part 2](part2/adding_detectors.md) - A basic example of how to create new detector geometries, add new sensitive detector constructors, and extend existing detector libraries.
 
+- [Part 3](part3/running_juggler.md) - Running Juggler  reconstruction
+
 
 ## Background Discussion