Add clarifying comment for bugfix

tesseract_task_composer/planning/src/nodes/upsample_trajectory_task.cpp

@@ -137,7 +137,7 @@ void UpsampleTrajectoryTask::upsample(CompositeInstruction& composite,
       if (start_instruction.isNull())
       {
         start_instruction = i.as<MoveInstructionPoly>();
-        composite.push_back(i);
+        composite.push_back(i); // Prevents loss of very first waypoint when upsampling
         continue;
       }