Added some tips about ros2 pkg list.

Author: Murilo Marinho

docs/source/advanced.rst

@@ -1,6 +1,9 @@
 Create packages (:program:`ros2 pkg create`)
 --------------------------------------------
 
+:program:`ROS2` packages are the most basic element in the :program:`ROS2` infrastructure. You must be able to create them correctly and consistently.
+Everything else that :program:`ROS2` can offer rotates about the effective use of packages.
+
 ROS2 has a tool to help create package templates. We can get all available options by running
 
 .. code-block:: console
@@ -10,7 +13,7 @@ ROS2 has a tool to help create package templates. We can get all available optio
 which outputs a list of handy options to populate the package template with useful files. Namely, the four emphasized ones.
 
 .. code-block:: console
-   :emphasize-lines: 19,21,27, 29
+   :emphasize-lines: 19,21,27,29
 
    usage: ros2 pkg create [-h] [--package-format {2,3}] [--description DESCRIPTION] [--license LICENSE] [--destination-directory DESTINATION_DIRECTORY] [--build-type {cmake,ament_cmake,ament_python}]
                     [--dependencies DEPENDENCIES [DEPENDENCIES ...]] [--maintainer-email MAINTAINER_EMAIL] [--maintainer-name MAINTAINER_NAME] [--node-name NODE_NAME] [--library-name LIBRARY_NAME]
@@ -41,4 +44,8 @@ which outputs a list of handy options to populate the package template with usef
      --node-name NODE_NAME
                            name of the empty executable
      --library-name LIBRARY_NAME
-                           name of the empty library
+                           name of the empty library
+
+Although it is recommended to use some of the other options as well, such as :code:`--license`, :code:`--maintainer-email`,
+and :code:`--maintainer-name`, they would make the commands too long for the purposes of this tutorial. Remember to choose
+the most suitable values for your application.

docs/source/create_packages.rst

@@ -25,6 +25,29 @@ As the workspace grows bigger and the packages more complex, figuring out such e
     colcon build
     source install/setup.bash
 
+Troubleshooting tips
+--------------------
+
+One important tool to assist in case your package is not found is :program:`ros2 pkg list`. It can be called as follows.
+
+.. code :: console
+
+   ros2 pkg list
+
+It will output a large number of packages even for the most basic installations of :program:`ROS2`. If you are looking for
+a particular package, you can use :program:`grep` which is more actively used (and explained) in other parts of this tutorial. For instance,
+if you are looking for :file:`python_package_with_a_node` you can do as follows.
+
+.. code :: console
+
+   ros2 pkg list | grep the_simplest_python_package
+
+This will either output nothing if the package is not found or it will output the name of the package, as follows.
+
+.. code :: console
+
+   grep the_simplest_python_package
+
 .. admonition:: Hint for the future you
 
    In rare cases, the workspace can be left in an unclean state in which older build artifacts cause build and runtime issues, such as failed builds and programs that do not seem to match their intended source code. These artifacts might include old files that should have been removed, issues with dependencies, and so on. In those cases, it might be good to remove the :file:`build`, :file:`install`, and :file:`log` folders before rebuilding and re-sourcing.