fix readme

Author: Ar-Ray-code

README.md

@@ -183,6 +183,7 @@ ros2 launch yolox_ros_py yolox_nano_onnx_gazebo.launch.py
 ```bash
 # git clone https://github.com/Ar-Ray-code/YOLOX-ROS.git --recursive
 vcs import . < YOLOX-ROS/youtube-publisher.repos
+pip3 install -r YOLOX-ROS/requirements.txt
 pip3 install -r YouTube-publisher-ROS2/requirements.txt
 cd ..
 colcon build --symlink-install --pacakges-select yolox_ros_py bboxes_ex_msgs youtube_publisher