Gaboardi/ORNL Acknowledgement

[jGaboardi]

This PR adds an acknowledgment to the JOSS submission that applies only to me with the following language:

The following acknowledgement applies to James D. Gaboardi (affiliation 4) only:

This manuscript has been authored by UT-Battelle LLC under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-public-access-plan).