refactor: update CHANGELOG

Author: rickstaa

CHANGELOG.md

@@ -6,7 +6,7 @@
   - Add JointPosition and JointVelocity Interface
   - Fix: Robot now keeps position when no controller is running
   - joint_{position,velocity}_example controller are now available in `franka_gazebo`
-
+  - Add Gazebo simulation physics engine command line argument.
 
 ## 0.8.2 - 2022-02-22