Fix executable name in README (#125)

Co-authored-by: Yun Ding <[email protected]>

Author: GeauxEric

README.md

@@ -90,15 +90,15 @@ Publisher:
 ```
 # Do this in a new terminal
 . ./install/setup.sh
-ros2 run rclrs_examples rclrs_publisher
+ros2 run rclrs_examples minimal_publisher
 ```
 
 Subscriber:
 
 ```
 # Do this in a new terminal
 . ./install/setup.sh
-ros2 run rclrs_examples rclrs_subscriber
+ros2 run rclrs_examples minimal_subscriber
 ```
 
 Enjoy!