Revert "chapt9中修改gazebo启动文件 (#13)"

This reverts commit 3f9654d7113fac6e3dce63009efce26cf2fb051c.

docs/humble/chapt9/get_started/3.在Gazebo加载机器人模型.md

@@ -236,7 +236,7 @@ def generate_launch_description():
 
     # Start Gazebo server
     start_gazebo_cmd =  ExecuteProcess(
-        cmd=['gazebo', '--verbose','-s', 'libgazebo_ros_init.so', '-s', 'libgazebo_ros_factory.so'],
+        cmd=['gazebo', '--verbose','-s', 'libgazebo_ros_init.so', '-s', 'libgazebo_ros_factory.so', gazebo_world_path],
         output='screen')
 
     # Launch the robot