cosmetic changes to Chapter's READMEs

Author: CamDavidsonPilon

Chapter1_Introduction/README.md

@@ -1,19 +1,25 @@
 # Chapter 1
 
-Instructions on Usage of the iPython Notebook for Chapter 1. There are 2 options available to the learner.
+Instructions on Usage of the IPython Notebook for Chapter 1. There are 3 options available to the learner.
 
 ### Option 1
 ------------
-The lesson was created with iPython Notebook. It allows a user to interact with the contents of the notebook. 
+The lesson was created with IPython Notebook. It allows a user to interact with the contents of the notebook. 
 
-If you do not have iPython Notebook installed you can use Option 2 to review the material. The lesson will not be interactive.
+*If you do not have IPython Notebook installed, you can use Option 2 or 3 to review the material. The lesson will not be interactive.*
 
 
 ### Option 2
 -------------
+PDFs of the chapters are available [online](https://github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers/tree/master/previews).
+
+
+### Option 3
+-------------
 Open with your browser: http://nbviewer.ipython.org/urls/raw.github.com/CamDavidsonPilon/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers/master/Chapter1_Introduction/Chapter1_Introduction.ipynb
 
 #### Screenshot of notebook for Chapter 1
 ---------------
 ![alt text][logo]
 [logo]: https://raw.github.com/bigsnarfdude/Probabilistic-Programming-and-Bayesian-Methods-for-Hackers/master/Chapter1_Introduction/Screen%20Shot%202013-02-06%20at%205.52.18%20PM.png "Chapter 1 iPython Notebook Screenshot"
+