Fix ordering and update contribution guide

CONTRIBUTING.md

@@ -5,6 +5,7 @@ Please ensure your pull request adheres to the following guidelines:
 - Search previous suggestions before making a new one, as yours may be a duplicate.
 - if you want to add a new book you should have read the book.
 - Use the following format: `| Book name | Author | [Goodreads rating](Goodreads url) | Year published |`
+- Order the entry within its section based on the Goodreads rating.
 - Mention in pull request clearly why you think the book deserve to be in the list.
 
 Thank you!

README.md

@@ -411,9 +411,9 @@ If you like Mind Expanding books you should check out my new project http://diff
 | His Dark Materials | Philip Pullman | [4.25](https://www.goodreads.com/book/show/18116.His_Dark_Materials) |  |  
 | The Last Wish - Saga | Andrzej Sapkowski | [4.2](https://www.goodreads.com/book/show/1128434.The_Last_Wish) | 1993 |
 | The Chronicles of Narnia | Clive Staples Lewis | [4.24](https://www.goodreads.com/book/show/11127.The_Chronicles_of_Narnia) | 2002 |  
-| The City & The City | China Mieville | [3.91](https://www.goodreads.com/book/show/4703581-the-city-the-city) | 2009 |  
-| The Broken Empire | Mark Lawrence | [3.87](https://www.goodreads.com/series/64473-the-broken-empire) | 2011 |
 | The Wheel of Time | Robert Jordan | [4.19](https://www.goodreads.com/series/41526-the-wheel-of-time) | 1990 |
+| The City & The City | China Mieville | [3.91](https://www.goodreads.com/book/show/4703581-the-city-the-city) | 2009 |  
+| The Broken Empire | Mark Lawrence | [3.87](https://www.goodreads.com/series/64473-the-broken-empire) | 2011 |  
 
 ### Historical Fiction
 | Name | Author | Goodreads Rating | Year Published |