[gazebo] Added information about some vendor packages as examples.

Author: Murilo Marinho

docs/source/gazebo/installation.rst

@@ -91,8 +91,70 @@ We can start by choosing the file :file:`ackermann_steering.sdf`
 .. _gnupg: https://gnupg.org/download/
 
 
-:program:`Gazebo` and :program:`rviz2`
---------------------------------------
+:program:`Gazebo` and :program:`ROS2` structure
+-----------------------------------------------
+
+A :program:`Gazebo`\-related development in :program:`ROS2` will generally have four packages for each robot or system.
+One example is shown below, in the official https://github.com/gazebosim/ros_gz_project_template.
+
+.. code-block::
+    :emphasize-lines: 2,5,10,15
+
+    .
+    |-- ros_gz_example_application
+    |   |-- CMakeLists.txt
+    |   `-- package.xml
+    |-- ros_gz_example_bringup
+    |   |-- CMakeLists.txt
+    |   |-- config
+    |   |-- launch
+    |   `-- package.xml
+    |-- ros_gz_example_description
+    |   |-- CMakeLists.txt
+    |   |-- hooks
+    |   |-- models
+    |   `-- package.xml
+    `-- ros_gz_example_gazebo
+        |-- CMakeLists.txt
+        |-- README.md
+        |-- hooks
+        |-- include
+        |-- package.xml
+        |-- src
+        `-- worlds
+
+This means that if you were to develop packages for a robot called ``beautiful_bot`` you'd be expected to create the four packages as follows.
+
+.. code-block::
+
+    .
+    |-- beautiful_bot_application
+    |-- beautiful_bot_bringup
+    |-- beautiful_bot_description
+    `-- beautiful_bot_gazebo
+
+According to the developers `here <https://gazebosim.org/docs/harmonic/ros_gz_project_template_guide/>`_ and `here <https://github.com/gazebosim/docs/issues/580>`_, our hypotetical packages would have the following roles.
+
+================================= ==================================
+:file:`beautiful_bot_application` :program:`ROS2`\-specific code.
+:file:`beautiful_bot_bringup`      Project's main launch files and robot configuration.
+:file:`beautiful_bot_description` The :file:`.sdf` files for robots and other simulation things.
+:file:`beautiful_bot_gazebo`      World :file:`.sdf` file and :Program:`Gazebo` configuration.
+================================= ==================================
+
+If you explore the :program:`ROS` packages made avialable by vendors, you will notice this structure or part of it. Some examples
+
+- `Denso <https://github.com/DENSORobot/denso_robot_ros2>`_
+- `Kawasaki <https://github.com/Kawasaki-Robotics/khi_robot>`_
+- `Franka <https://github.com/frankarobotics/franka_ros2>`_
+
+.. important::
+
+    Owing to the lifecycle of products and resource allocation (we also suffer from this at Universities), you can always expect the official packages for :program:`ROS2` and
+    :program:`Gazebo` shipped officially by vendors to considerably lag behind.
+
+:program:`Gazebo` and :program:`ROS2` example
+---------------------------------------------
 
 .. note::