Update _docs/concepts/client_library/execution_management/index.md

Co-authored-by: Ralph Lange <ralph-lange@users.noreply.github.com>

Author: JanStaschulat

_docs/concepts/client_library/execution_management/index.md

@@ -133,7 +133,7 @@ Figure 4: Multiple sensors driving a Sense-Plan-Act pipeline.
 
 Typically multiple sensors are used to perceive the environment. For example an IMU and a laser scanner. The quality of localization algorithms highly depend on how old such sensor data is when it is processed. Ideally the latest data of all sensors should be processed. One way to achive this is to execute first all sensor drivers in the sense-phase and then process all algorithms in the plan-phase.
 
-Currently, such a processing order cannot be defined with the default ROS2 Executor. One could in principle design a data-driven pipeline, however if e.g. the Laser scan is needed by some other callback in the sense-phase as well as in the plan-phase, the processing order of these subscribers is arbitrary.
+Currently, such a processing order cannot be defined with the default Executor of rclcpp. One could in principle design a data-driven pipeline, however if e.g. the Laser scan is needed by some other callback in the sense-phase as well as in the plan-phase, the processing order of these subscribers is arbitrary.
 
 For this sense-plan-act pattern, we could define one executor for each phase. The plan-phase would be triggered only when all callbacks in the sense-phase have finished.