message: Add citation to readme
diff: @@ -134,6 +134,19 @@ The viewer application and the examples use the following third-party libraries
  - [RapidJSON](http://rapidjson.org/) library for parsing JSON scene descriptions.
  - [tinyply](https://github.com/ddiakopoulos/tinyply) library to load Stanford PLY models.
  +### Citation
  +
  +If you use Visionaray or some of its code for your scientific project, it would be nice if you cited this paper:
  +```
  +@inproceedings{zellmann:visionaray,
  +author = {Zellmann, Stefan and Wickeroth, Daniel and Lang, Ulrich},
  +title = {Visionaray: A Cross-Platform Ray Tracing Template Library},
  +booktitle = {Proceedings of the 10th Workshop on Software Engineering and Architectures for Realtime Interactive Systems (IEEE SEARIS 2017)},
  +year = {2017},
  +publisher = {IEEE}
  +}
  +```
  +
  License
  -------
  