Enable zenohd to make the post-install example work for Ubuntu Debian. (#5860)

Signed-off-by: Tomoya.Fujita <[email protected]>
Signed-off-by: Alejandro Hernández Cordero <[email protected]>
Co-authored-by: Alejandro Hernández Cordero <[email protected]>

Author: fujitatomoya

source/Installation/Ubuntu-Install-Debs.rst

@@ -97,14 +97,23 @@ Try some examples
 
 If you installed ``ros-{DISTRO}-desktop`` above you can try some examples.
 
-In one terminal, source the setup file and then run a C++ ``talker``\ :
+First, if you use ``Zenoh`` as the RMW implementation, you will require a router for node discovery and communication.
+
+In one terminal, start the Zenoh router daemon:
+
+.. code-block:: console
+
+   $ source /opt/ros/{DISTRO}/setup.bash
+   $ ros2 run rmw_zenoh_cpp rmw_zenohd
+
+In another terminal, source the setup file and then run a C++ ``talker``\ :
 
 .. code-block:: console
 
    $ source /opt/ros/{DISTRO}/setup.bash
    $ ros2 run demo_nodes_cpp talker
 
-In another terminal source the setup file and then run a Python ``listener``\ :
+In a third terminal source the setup file and then run a Python ``listener``\ :
 
 .. code-block:: console