Update README.md

Author: CamDavidsonPilon

README.md

@@ -154,11 +154,12 @@ Reviews
 The publishing model is so unusual. Not only is it open source but it relies on pull requests from anyone in order to progress the book. This is ingenious and heartening" - [excited Reddit user](http://www.reddit.com/r/Python/comments/1alnal/probabilistic_programming_and_bayesian_methods/)
 
 
-Available for ALL the mobile devices, as these real-life screen shots suggest:
+Available for ALL the mobile devices, as these real-life screenshots suggest:
 
 ![so real](http://i.imgur.com/6jV4mSr.png)
 ![really real](http://i.imgur.com/JMdYv6g.png)
 
+(thanks to [http://placeit.breezi.com/](http://placeit.breezi.com/) for these hilarious shots)
 
 Contributions and Thanks
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