Add --reproduce-command in UC install and upgrade.

Document the usage of the --reproduce-command option to obtain a
reproducer file with the Ansible command used to re-run the very
same deployment playbooks.

Depends-On: https://review.opendev.org/c/openstack/python-tripleoclient/+/827494
Change-Id: Id136969eaef3a1a911c1132bdc696181039e787c

deploy-guide/source/deployment/install_undercloud.rst

@@ -254,6 +254,11 @@ Downloaded ansible playbooks and inventory files (see :ref:`config_download`)
 used for undercloud deployment are stored in the tempdir
 ``~/undercloud-ansible-<XXXX>`` by default.
 
+.. note::
+    In order to obtain the ansible command used for the installation of the
+    Undercloud in the artifacts directory, it is necessary to pass the option
+    ``--reproduce-command`` in the Undercloud deployment command.
+
 .. note::
     Any passwords set in ``undercloud.conf`` will take precedence over the ones in
     ``undercloud-passwords.conf``.

deploy-guide/source/post_deployment/upgrade/undercloud.rst

@@ -128,6 +128,11 @@ Updating Undercloud Components
        To upgrade with instack undercloud in Rocky, you'll need to upgrade with
        ``--use-heat=False`` option. Note this isn't tested and not supported.
 
+   .. note::
+       In order to obtain the ansible command used for the installation of the
+       Undercloud in the artifacts directory, it is necessary to pass the option
+       ``--reproduce-command`` in the Undercloud upgrade command.
+
    .. note::
        It's possible to enable verbose logging with ``--verbose`` option.
        To cleanup an undercloud after its upgrade, you'll need to set