Modified Luanch files tutorial, added a note to the README.

README.md

@@ -29,6 +29,8 @@ Below are some links to help with the ports.
 
 ## MoveIt Tutorials Source Build
 
+(This section can be skipped if you aren't adding executable code. You don't need to build MoveIt to add an explanation about something.)
+
 Follow the [MoveIt Source Build](https://moveit.ros.org/install-moveit2/source/) instructions to set up a colcon workspace with MoveIt from the source.
 
 Open a command line to your colcon workspace:

doc/how_to_guides/moveit_launch_files/moveit_launch_files_tutorial.rst

@@ -44,10 +44,44 @@ A handy way to refer to a MoveIt configuration package is to use the ``MoveItCon
         .to_moveit_configs()
     )
 
+``MoveItConfigsBuilder`` (`defined here <https://github.com/moveit/moveit2/blob/main/moveit_configs_utils/moveit_configs_utils/moveit_configs_builder.py>`_) can take a few different types of arguments.
+``MoveItConfigsBuilder(package_name="package_name")``  will search for a package named "package_name".
+``MoveItConfigsBuilder("robot_name")`` will search for an explicitly given package name.
+Both arguments can be given, in which case the robot name is stored and the package with the explicitly given name will be loaded.
+As seen above, ``gen3`` is the robot name, and MoveIt looks for the package ``kinova_gen3_7dof_robotiq_2f_85_moveit_config`` instead of ``gen3_moveit_config``.
+
+``.robot_description`` can optionally take a file path to ``robot_name.urdf`` and/or assign a dictionary of argument mappings that are passed to the robot's urdf.xacro file.
+The file path to ``robot_name.urdf`` must be relative to your robot package, so if your robot package is ``/robot_package`` and the urdf (or urdf xacro) file is ``robot_package/config/robot_name.urdf``
+you would pass ``.robot_description(filepath="config/robot_name.urdf")``.
+If you don't provide a file path, but you do give ``MoveItConfigsBuilder`` a robot name (see above paragraph), MoveIt will look for ``robot_package/config/robot_name.urdf``.
+
+``.trajectory_execution`` loads trajectory execution and MoveIt controller manager's parameters from an optionally provided file path.
+If a file path isn't given, MoveIt looks for files in the package's ``config`` folder for files ending with ``controllers.yaml``.
+
+``.planning_scene_monitor`` allows you to set various parameters about what scene information is published and how often is it published.
+
+``.planning_pipelines`` allows to you to list the names of the planners you want available to be used by your robot.
+If you opt to not list pipelines, as in ``.planning_pipelines()``, MoveIt will look in the config folder of your package for files that end with "_planning.yaml".
+Additionally, if no pipelines are listed, MoveIt will load a set of planners from its own library - this can be disabled adding ``load_all=False`` as an argument to ``.planning_pipelines``.
+Listing the planner names specifiies which planners MoveIt should load; again these should be in your config folder.
+MoveIt will also pick one of your planners to be the default planner.
+If OMPL is one of your planners, it will be the default planner unless you set ``default_planning_pipeline`` to your desired default planner as in
+
+.. code-block:: python
+
+    .planning_pipelines(
+            pipelines=["ompl", "your_favorite_planner"],
+            default_planning_pipeline="your_favorite_planner",
+        )
+
+If OMPL is not in your planner list and you don't set a default planner, MoveIt will pick the first planner in the list.
+
+
+
 Launching Move Group
 --------------------
 
-Once all the MoveIt configuration parameters have been loaded, you can launch the :ref:`Move Group Interface` using the entire set of loaded MoveIt parameters.
+Once all the MoveIt configuration parameters have been loaded, you can define the :ref:`Move Group Interface` Node using the entire set of loaded MoveIt parameters.
 
 .. code-block:: python
 
@@ -187,6 +221,7 @@ In our example, we have:
         arguments=["robotiq_gripper_controller", "-c", "/controller_manager"],
     )
 
+
 Launching all the nodes
 -----------------------
 
@@ -213,3 +248,23 @@ Finally, we can tell our launch file to actually launch everything we described
                 hand_controller_spawner,
             ]
         )
+
+Launching a custom .cpp file
+----------------------------
+
+While not part of the Getting Started tutorial, another common node to launch is one that executes a custom .cpp file:
+
+.. code-block:: python
+
+    moveit_cpp_node = Node(
+        name="custom_program",
+        package="custom_program_package",
+        executable="custom_program",
+        output="screen",
+        parameters=[your,
+                    parameters,
+                    here],
+    )
+
+where ``moveit_cpp_node_parameters`` is a list of parameters for that node. See Ros2 documentation for more information on launching .cpp files.
+Additionally, the tutorials on this site provide more examples on how to create programs to customize MoveIt's capabilities for your project.