Update README.rst

Author: manodeep

README.rst

@@ -4,10 +4,16 @@ Description
 This repo contains 2LPT IC generation code from Roman Scoccimarro. 
 Original code can be found `here <http://cosmo.nyu.edu/roman/2LPT/>`__
 
-The code has been updated with lots of checks about INT overflow and 
-64 bit IDs. Dependency on Numerical Recipes in C has been replaced 
-with ``gsl``. This code can accept P(k) generated by 
-`CAMB <http://camb.info/>`__.
+Improvements
+============
+
+1. The code has been updated with lots of checks about INT overflow and 64 bit ID overflows. 
+2. Dependency on Numerical Recipes in C has been replaced with ``gsl`` 
+3. This code can accept P(k) generated by `CAMB <http://camb.info/>`__ (contribution from Greg Poole) 
+4. Can generate consistent particle IDs across simulations of different resolutions (contribution from Greg Poole)
+
+**Note** this version produces a header compatible with standard public Gadget2. In particular, 
+the number of particles in excess of INT_MAX (~2e9) is stored in ``npartTotalHighWord`` in the header, rather than npartTotal[2].
 
 Installation
 ============