2.6 changelog gen/version/root dir cleanup (#40421)

* patched in changelog gen stuff from stable-2.5
* Makefile updates
* release.py as single-source-of-truth
* Remove obsolete ansible-core-sitemap.xml file.
* Move ROADMAP.rst into README.rst.
* dynamic rpm changelog, zap old deb/rpm changelogs
* fix changelog in MANIFEST.in
* Remove obsolete hacking/update.sh script.
* Remove ref to deleted authors script.
* Remove ref to removed module-formatter script.
* Update headings to match script names.
* MANIFEST.in cleanup
* removed RELEASES.txt and versions.yml
* removed obsolete release generation playbook/bits (not used since 2.5)
* misc Makefile cleanup
* speculative changes to DEB versioning
* allow override of DEB_VERSION/DEB_RELEASE

hacking/ticket_stubs/bug_internal_api.md

@@ -0,0 +1,16 @@
+Internal Ansible API
+====================
+
+Hi!
+
+Thanks very much for your submission to Ansible.  It sincerely means a lot to us
+to have an active community that is willing to submit feedback so that we may
+continue to make Ansible better.
+
+The internal Python API is considered an unsupported aspect of Ansible and this
+is not considered a bug unless there is an issue with an Ansible binary
+(`ansible`, `ansible-playbook`, `ansible-doc`, etc) or an issue with an external
+API such as are provided for the development of plugins (modules, dynamic
+inventories, callbacks, strategies, etc).
+
+Thank you once again for this and your interest in Ansible!