adding prolouge.ipynb and adding to README

Author: CamDavidsonPilon

README.md

@@ -20,6 +20,8 @@ Contents
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 (This is all rendered via the *nbviewer* is is read-only. Editable notebooks + examples can be downloaded too by forking! )
+
+
 0\. [**Prolouge**](http://nbviewer.ipython.org/urls/raw.github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers/master/Prolouge/Prolouge.ipynb)Why we do it.
 
 1. [**Chapter 1: Introduction to Bayesian Methods**](http://nbviewer.ipython.org/urls/raw.github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers/master/Chapter1_Introduction/Chapter1_Introduction.ipynb)