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_cannot_reproduce.md

@@ -0,0 +1,26 @@
+Cannot Reproduce
+================
+
+Hi!
+
+Thanks very much for your submission to Ansible.  It sincerely means a lot to us. 
+
+Testing this on the version you have specified, we cannot reproduce this problem.
+
+Our reasons and evidence for this are:
+
+   * INSERT HERE
+
+And we suggest that:
+
+   * INSERT THINGS TO DO HERE
+
+As such, we are most likely going to close this ticket.  Should you disagree with this conclusion, you may also wish to join our mailing lists, which are very active:
+
+   * https://groups.google.com/forum/#!forum/ansible-project - for user questions, tips, and tricks
+   * https://groups.google.com/forum/#!forum/ansible-devel - for strategy, future planning, and questions about writing code
+
+Thank you once again for this and your interest in Ansible!
+
+
+