Add a script to generate a new porting guide

* porting-guide.py is allowed to be Python-3.6+ as it will only be run
  by release engineers

docs/docsite/rst/porting_guides/porting_guide_2.9.rst

@@ -0,0 +1,78 @@
+
+.. _porting_2.9_guide:
+
+*************************
+Ansible 2.9 Porting Guide
+*************************
+
+This section discusses the behavioral changes between Ansible 2.8 and Ansible 2.9.
+
+It is intended to assist in updating your playbooks, plugins and other parts of your Ansible infrastructure so they will work with this version of Ansible.
+
+We suggest you read this page along with `Ansible Changelog for 2.9 <https://github.com/ansible/ansible/blob/devel/changelogs/CHANGELOG-v2.9.rst>`_ to understand what updates you may need to make.
+
+This document is part of a collection on porting. The complete list of porting guides can be found at :ref:`porting guides <porting_guides>`.
+
+.. contents:: Topics
+
+
+Playbook
+========
+
+No notable changes
+
+
+Command Line
+============
+
+No notable changes
+
+
+Deprecated
+==========
+
+No notable changes
+
+
+Modules
+=======
+
+No notable changes
+
+
+Modules removed
+---------------
+
+The following modules no longer exist:
+
+* No notable changes
+
+
+Deprecation notices
+-------------------
+
+No notable changes
+
+
+Noteworthy module changes
+-------------------------
+
+No notable changes
+
+
+Plugins
+=======
+
+No notable changes
+
+
+Porting custom scripts
+======================
+
+No notable changes
+
+
+Networking
+==========
+
+No notable changes