Added URL for GitHub in suggested acknowledgement text

Signed-off-by: Marshall J. Styczinski <itsmoosh@gmail.com>

README.md

@@ -4,7 +4,7 @@ Software framework for constructing 1D interior structure models based on planet
 The main repository is mirrored at https://github.com/NASA-Planetary-Science/PlanetProfile; any pull requests should be submitted to https://github.com/vancesteven/PlanetProfile.
 
 ## Acknowledging PlanetProfile
-We want to hear about your work with PlanetProfile! Please consider sending us a message alerting us to your work (svance@jpl.nasa.gov). Suggested acknowledgement in publications: "Data used in this work were generated using the open-source PlanetProfile software hosted on GitHub."
+We want to hear about your work with PlanetProfile! Please consider sending us a message alerting us to your work (svance@jpl.nasa.gov). Suggested acknowledgement in publications: "Data used in this work were generated using the open-source _PlanetProfile_ software hosted on GitHub (https://github.com/vancesteven/PlanetProfile)."
 
 ## Getting started
 PlanetProfile is available in Python and Matlab.