Point to bib file in readme

Author: A-CGray

README.md

@@ -4,6 +4,8 @@ This repo contains files related to the "MACH Tutorial Wing", a proposed benchma
 
 For more details on the wing model and the corresponding benchmark optimization problems, see our paper "A Proposed Benchmark Model for Practical Aeroelastic Optimization of Aircraft Wings".
 
+If you use this model and/or the benchmark problems in your research, please cite the paper, a bibtex entry is provided in `CITATION.bib`.
+
 This repo includes:
 
 - OML and wingbox CAD files