Add navigation and SLAM demos (in simulation) (#1022) (#1052)

(cherry picked from commit f977222)

Co-authored-by: Darko Lukić <lukicdarkoo@gmail.com>
(cherry picked from commit ed58ce1)

source/Tutorials.rst

@@ -146,6 +146,8 @@ Demos
 * `Turtlebot 2 demo using ROS 2 <https://github.com/ros2/turtlebot2_demo>`__.
 * `TurtleBot 3 demo using ROS 2 <http://emanual.robotis.com/docs/en/platform/turtlebot3/ros2_setup/>`__. [community-contributed]
 * `Simulate the TurtleBot 3 on ROS [community-contributed] <https://ubuntu.com/blog/simulate-the-turtlebot3>`__.
+* `Navigate TurtleBot 3 in simulation <https://github.com/cyberbotics/webots_ros2/wiki/Navigate-TurtleBot3>`__. [community-contributed]
+* `SLAM with TurtleBot3 in simulation <https://github.com/cyberbotics/webots_ros2/wiki/SLAM-with-TurtleBot3>`__. [community-contributed]
 * `MoveIt 2 demo using ROS 2 <https://github.com/ros-planning/moveit2/tree/master/moveit_demo_nodes/run_moveit_cpp>`__.
 * `Using tf2 with ROS 2 <Tutorials/tf2>`.
 * `Using URDF with robot_state_publisher <Tutorials/URDF/Using-URDF-with-Robot-State-Publisher>`.