Baseline changes to comply with Release Notes Management
based in Reno [0]:
* Use build-openstack-releasenotes job for release notes
(We can't use the OpenStack releasenotes template as it includes
publish jobs, stx needs its own)
* Add newnote tox environment as convenience for creating new release
notes, re-using the releasenotes venv.
[0] https://docs.openstack.org/reno/latest/
Story: 2003101
Task: 26719
Change-Id: If4f8833fb4d3539ba47ce3014d4d3bbae409c278
Signed-off-by: Abraham Arce <abraham.arce.moreno@intel.com>
d59fe6623c