Document how to export deployment plans

Change-Id: I0176ddb63ee547364df08534acbaef348ae5c2be

doc/source/install/advanced_deployment/custom.rst

@@ -14,3 +14,4 @@ Documentation on how to deploy custom configurations with |project|.
    template_deploy
    deploy_swift
    role_specific_parameters
+   plan_export

doc/source/install/advanced_deployment/plan_export.rst

@@ -0,0 +1,40 @@
+Exporting Deployment Plans
+==========================
+
+Exporting a deployment plan enables you to quickly retrieve the contents of an
+existing deployment plan. A deployment plan consists of the heat templates and
+the environment files used to deploy an overcloud, as well as the
+`plan-environment.yaml`_ file which holds the plan metadata. Exporting a plan
+can be useful if you want to use an existing plan as a starting point for
+further customizations (instead of starting from scratch with a fresh copy of
+`tripleo-heat-templates`_).
+
+Exporting a plan using the CLI
+------------------------------
+
+To export a plan using the CLI, use the following command::
+
+    $ openstack overcloud plan export <plan_name>
+
+E.g::
+
+    $ openstack overcloud plan export overcloud
+
+will export the default plan called ``overcloud``. By default, a tarball named
+``overcloud.tar.gz`` containing the plan files will be created in the current
+directory. If you would like to use a custom file name, you can specify it
+using the ``--output-file`` option.
+
+Exporting a plan using the UI
+-----------------------------
+
+To export a plan using the UI, navigate to the ``Plans`` page using the
+``All Plans`` link from the ``Plans`` tab. Then open the kebab menu of the
+plan you want to export and click the ``Export`` link. This will trigger the
+plan export workflow and after the plan export completes you will be presented
+with a link to download the plan tarball.
+
+
+
+.. _`plan-environment.yaml`: https://github.com/openstack/tripleo-heat-templates/blob/master/plan-environment.yaml
+.. _`tripleo-heat-templates`: https://github.com/openstack/tripleo-heat-templates