move the exlpanation to How To Guide section.

Signed-off-by: Tomoya Fujita <Tomoya.Fujita@sony.com>

source/How-To-Guides.rst

@@ -43,6 +43,7 @@ If you are new and looking to learn the ropes, start with the :doc:`Tutorials <T
    How-To-Guides/Topics-Services-Actions
    How-To-Guides/Using-Variants
    How-To-Guides/Using-ros2-param
+   How-To-Guides/ZeroCopy-loaned-messages
 
 .. toctree::
   :hidden:

source/How-To-Guides/ZeroCopy-loaned-messages.rst

@@ -0,0 +1,55 @@
+.. _ZeroCopyLoanedMessages:
+
+Zero Copy Loaned Messages
+=========================
+
+.. contents:: Contents
+   :depth: 1
+   :local:
+
+See the `Loaned Messages <https://design.ros2.org/articles/zero_copy.html>`__ article for details on ``ROS_DISABLE_LOANED_MESSAGES`` environment variable.
+
+How to disable Loaned Messages
+------------------------------
+
+In default, *Loaned Messages* will try to borrow the memory from underlying middleware if it supports *Loaned Messages*.
+``ROS_DISABLE_LOANED_MESSAGES`` environment variable is provided to user that allows to disable *Loaned Messages* and fallback to normal publisher / subscription w/o any code change or middleware configuration.
+You can set the environment variable with the following command:
+
+.. tabs::
+
+   .. group-tab:: Linux
+
+      .. code-block:: console
+
+        export ROS_DISABLE_LOANED_MESSAGES=1
+
+      To maintain this setting between shell sessions, you can add the command to your shell startup script:
+
+      .. code-block:: console
+
+        echo "export ROS_DISABLE_LOANED_MESSAGES=1" >> ~/.bashrc
+
+   .. group-tab:: macOS
+
+      .. code-block:: console
+
+        export ROS_DISABLE_LOANED_MESSAGES=1
+
+      To maintain this setting between shell sessions, you can add the command to your shell startup script:
+
+      .. code-block:: console
+
+        echo "export ROS_DISABLE_LOANED_MESSAGES=1" >> ~/.bash_profile
+
+   .. group-tab:: Windows
+
+      .. code-block:: console
+
+        set ROS_DISABLE_LOANED_MESSAGES=1
+
+      If you want to make this permanent between shell sessions, also run:
+
+      .. code-block:: console
+
+        setx ROS_DISABLE_LOANED_MESSAGES 1

source/Tutorials/Configuring-ROS2-Environment.rst

@@ -196,53 +196,6 @@ Once you have determined a unique integer for your group of ROS 2 agents, you ca
 
         setx ROS_DOMAIN_ID <your_domain_id>
 
-3.2 The ``ROS_DISABLE_LOANED_MESSAGES`` variable
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-See the `Loaned Messages <https://design.ros2.org/articles/zero_copy.html>`__ article for details on ``ROS_DISABLE_LOANED_MESSAGES`` environment variable.
-
-In default, *Loaned Messages* will try to borrow the memory from underlying middleware if it supports *Loaned Messages*.
-``ROS_DISABLE_LOANED_MESSAGES`` environment variable is provided to user that allows to disable *Loaned Messages* and fallback to normal publisher / subscription w/o any code change or middleware configuration.
-You can set the environment variable with the following command:
-
-.. tabs::
-
-   .. group-tab:: Linux
-
-      .. code-block:: console
-
-        export ROS_DISABLE_LOANED_MESSAGES=1
-
-      To maintain this setting between shell sessions, you can add the command to your shell startup script:
-
-      .. code-block:: console
-
-        echo "export ROS_DISABLE_LOANED_MESSAGES=1" >> ~/.bashrc
-
-   .. group-tab:: macOS
-
-      .. code-block:: console
-
-        export ROS_DISABLE_LOANED_MESSAGES=1
-
-      To maintain this setting between shell sessions, you can add the command to your shell startup script:
-
-      .. code-block:: console
-
-        echo "export ROS_DISABLE_LOANED_MESSAGES=1" >> ~/.bash_profile
-
-   .. group-tab:: Windows
-
-      .. code-block:: console
-
-        set ROS_DISABLE_LOANED_MESSAGES=1
-
-      If you want to make this permanent between shell sessions, also run:
-
-      .. code-block:: console
-
-        setx ROS_DISABLE_LOANED_MESSAGES 1
-
 
 Summary
 -------