updated readme

README.md

 # nshmp-haz
 
-U.S. Geological Survey ([USGS](https://www.usgs.gov)) National Seismic Hazard Model Project
-([NSHMP](https://earthquake.usgs.gov/hazards/)) codes for performing probabilistic seismic
-hazard (PSHA) and related analyses. These codes are intended for use with seismic hazard models
-developed by the NSHMP for the U.S. and its territories. This project includes a variety of
-command line applications and web service classes and relies on the
-[*nshmp-lib*](https://code.usgs.gov/ghsc/nshmp/nshmp-lib) hazard library, among other
-dependencies.
-
-Please see the [docs](docs/README.md) for more information.
+U.S. Geological Survey ([USGS][1]) National Seismic Hazard Model Project ([NSHMP][2]) codes for
+performing probabilistic seismic hazard (PSHA) and related analyses. These codes are intended for
+use with seismic hazard models developed by the NSHMP for the U.S. and its territories. This
+project includes a variety of command line applications and web service classes and relies on the
+[*nshmp-lib*][3] hazard library, among other dependencies.
+
+Please see the [documentation](docs/README.md) for more information.
+
+DOI: https://doi.org/10.5066/P9STF5GK (version [2.0.0][4])
+
+[1]: https://www.usgs.gov
+[2]: https://www.usgs.gov/programs/earthquake-hazards/hazards
+[3]: https://code.usgs.gov/ghsc/nshmp/nshmp-lib
+[4]: https://code.usgs.gov/ghsc/nshmp/nshmp-haz/-/tags/2.0.0