Add sig-simulation to CODEOWNERS for the ROS2 Gem

Signed-off-by: Steve Pham <[email protected]>

.github/CODEOWNERS

@@ -23,6 +23,7 @@ Projects/OpenXRTest/ @o3de/sig-platform-reviewers @o3de/sig-platform-maintainers
 # SIG-Security
 
 # SIG-Simulation (@o3de/sig-simulation-reviewers @o3de/sig-simulation-maintainers)
+Gems/ROS2/ @o3de/sig-simulation-reviewers @o3de/sig-simulation-maintainers
 
 # SIG-Testing (@o3de/sig-testing-reviewers)