add citation file for GitHub support

Author: betaBison

CITATION.bib

@@ -0,0 +1,8 @@
+@inproceedings{knowlesmodular2022,
+   title = {A Modular and Extendable GNSS Python Library},
+   author={Knowles, Derek and Kanhere, Ashwin V and Bhamidipati, Sriramya and Gao, Grace},
+   booktitle={Proceedings of the 35th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2022)},
+   institution = {Stanford University},
+   year = {2022 [Online]},
+   url = {https://github.com/Stanford-NavLab/gnss_lib_py},
+}