Update README.md

Author: Nadrin

README.md

@@ -24,6 +24,7 @@ This project is still a work in progress. Items without a check mark are planned
 - [x] Unidirectional path tracing
 - [x] Multiple importance sampling (MIS)
 - [x] Next event estimation
+- [x] Russian Roulette path termination
 - [x] Physically based BRDF with metalness workflow (based on Unreal Engine 4 material model)
 - [x] Triangle mesh geometry
 - [x] Texture mapping (albedo, roughness & metalness maps)