Update readme.md

Including Python 2.7 pre-requisite in the documentation

README.md

@@ -18,6 +18,8 @@ Single-axis tracking is supported, and hourly output files based on TMY inputs
 are saved.  Spatial nonuniformity is reported, with multiple rear-facing irradiances collected
 on the back of each module row.
 
+## Pre-requisites
+This software is written for Anaconda Python 2.7 which can be downloaded here: https://www.anaconda.com/download/
 
 ## Install using pip
 
@@ -65,4 +67,4 @@ View Factor helper files to help with configuration-factor calculation
 1-axis tracking and self-shading calculation.
 Subroutines include:
 getBackSurfaceIrradiances, getFrontSurfaceIrradiances, getGroundShadeFactors,
-getSkyConfigurationFactors, trackingBFvaluescalculator, rowSpacing
+getSkyConfigurationFactors, trackingBFvaluescalculator, rowSpacing