fix github link (ros-navigation#860)

Signed-off-by: EricoMeger <ericomeger9@gmail.com>
Signed-off-by: Jaerak Son <sjr9017@naver.com>

Author: EricoMeger

configuration/packages/configuring-following-server.rst

@@ -5,7 +5,7 @@ Following Server
 
 Source code on Github_.
 
-.. _Github: https://github.com/ros-navigation/navigation2/nav2_following/opennav_following
+.. _Github: https://github.com/ros-navigation/navigation2/tree/main/nav2_following/opennav_following
 
 The Following Server in ``opennav_following`` implements a server for following dynamic objects from a detection topic or specific reference frame.
 This server allows the robot to follow and maintain a determined distance from a detected object or specific frame,