Fix sdformat_urdf README link in documentation (gazebosim#644)

Updated the link for sdformat_urdf README to the rolling branch.

Signed-off-by: Nguyễn Tấn Anh Khoa <[email protected]>

Author: kitare17

jetty/ros2_integration.md

@@ -205,7 +205,7 @@ A video walk-through of this tutorial is available from our YouTube channel: [Ga
 Take a step further and try out demos from [`ros_gz_sim_demos`](https://github.com/gazebosim/ros_gz/tree/ros2/ros_gz_sim_demos).
 
 For the `sdf_parser` demo, install [`ros_gz`](https://github.com/gazebosim/ros_gz/tree/ros2) and the parser plugin `sdformat_urdf` from source in a colcon workspace.
-Read more about `sdformat_urdf` [here](https://github.com/ros/sdformat_urdf/blob/ros2/sdformat_urdf/README.md).
+Read more about `sdformat_urdf` [here](https://github.com/ros/sdformat_urdf/blob/rolling/sdformat_urdf/README.md).
 
 Run the demo launch file with the rviz launch argument set:
 
@@ -243,4 +243,4 @@ Gazebo implements these interfaces, enabling you to,
 - Retrieve simulator information
 
 For a full tutorial, including usage examples for each interface see
-[Use ROS 2 Simulation Interfaces with Gazebo](ros2_sim_interfaces).
+[Use ROS 2 Simulation Interfaces with Gazebo](ros2_sim_interfaces).