Added part about python

README.md

@@ -10,7 +10,8 @@ version of the SWIFT code, available at:
 https://www.github.com/swiftsim/swiftsim
 
 You should then be able to follow the individual README's in each
-directory of figures/<x> to produce the plots. All of the LaTeX files
+directory of figures/<x> to produce the plots, assuming you have `python3`
+installed along with standard scientific packages. All of the LaTeX files
 are made available for use also.
 
 For questions, please contact: