fix comments for clarity

Signed-off-by: Tomohito Ando <tomohito.ando@tier4.jp>

Author: TomohitoAndo

planning/behavior_velocity_traffic_light_module/src/scene.cpp

@@ -281,21 +281,25 @@ bool TrafficLightModule::isStopSignal()
 {
   updateTrafficSignal();
 
-  // If it never receives traffic signal, it will PASS.
+  // Pass through if no traffic signal information has been received yet
+  // This is to prevent stopping on the planning simulator
   if (!planner_data_->has_received_signal_) {
     return false;
   }
 
-  // If the signal data is not received, the ego stops.
+  // Stop if there is no upcoming traffic signal information
+  // This is to safely stop in cases such that traffic light recognition is not working properly or
+  // the map is incorrect
   if (!traffic_signal_stamp_) {
     return true;
   }
 
-  // If the signal data is timeout, the ego stops.
+  // Stop if the traffic signal information has timed out
   if (isTrafficSignalTimedOut()) {
     return true;
   }
 
+  // Check if the current traffic signal state requires stopping
   return traffic_light_utils::isTrafficSignalStop(lane_, looking_tl_state_);
 }