Provide guidance about preferring openstackclient for CLI

Update a code-convention to use OpenStackClient as the example. Also
update the ui-terminology doc to add a note about using OpenStackClient
and not per-project CLI tools.

Change-Id: I167c82f9aa2cc6140d68e61d47af4c0230fb33a6

doc/doc-contrib-guide/source/writing-style/code-conventions.rst

@@ -13,9 +13,8 @@ Follow these guidelines:
 
 * **Use "--option ARGUMENT"**
 
-  The OpenStack CLI commands such as ``keystone`` support both
-  ``--option ARGUMENT`` and ``--option=ARGUMENT``. In technical publications,
-  use ``--option ARGUMENT``.
+  The OpenStack CLI supports both ``--option ARGUMENT`` and
+  ``--option=ARGUMENT``. In technical publications, use ``--option ARGUMENT``.
 
 * **Use "." to source script files**
 

doc/doc-contrib-guide/source/writing-style/ui-terminology.rst

@@ -30,6 +30,9 @@ When documenting actions that readers must perform in a command-line interface
   the output. Use ellipses (...) to show that the page displays a portion of
   the output.
 
+* Always use the OpenStack Client ``openstack`` for CLI commands rather than
+  per-project CLI tools such as ``nova``.
+
 * Depending on whether you describe CLI actions in the running text or
   in procedures, consider the following usage:
 
@@ -43,9 +46,10 @@ When documenting actions that readers must perform in a command-line interface
          between the two devices.
        - You can use the :command:`ping` command to verify the network
          connection between the two devices.
-     * - You can use :command:`nova image-create` command to take a snapshot.
-       - You can use the :command:`nova image-create` command to take
-         a snapshot.
+     * - You can use :command:`openstack server image create` command to take a
+         snapshot.
+       - You can use the :command:`openstack server image create` command to
+         take a snapshot.
 
   |