Check/fix USG copyright/TMs on 18 OASIS Open Repos - e.g. cti-stix-elevator

Urls: Go to https://github.com/oasis-open and search for 'cti' in 'Find a repository'

Status:

Many of the LICENSE.md files have an OASIS copyright line at the top, followed by the open source license chosen (e.g. BSD-3). No mention of US Government copyrights.

Corrections:

As these are open source projects, sponsored by the TC, and open to public review and contribution, we will add US Government copyright line below OASIS copyright to those repos stating the OASIS copyright. Any repos that lack a copyright statements will be left as is.