Add the openstack-security-notes project

This adds a new project that will be used by the OpenStack Security
Group (OSSG) for review and source control of OpenStack Security Notes
(OSSNs).

This new project will live under the Documentation program, which has
been agreed upon by the Documentation and OSSG groups.  The discussion
about this decision is in the referenced launchpad bug.

Closes-bug: 1279074
Change-Id: I3d4e0b2c9ab9df9f5f044ddf46c4aff2a01a967a
Merge "Add the openstack-security-notes project"