update README.rst

Author: ikreymer

README.rst

@@ -3,11 +3,11 @@ PyWb 0.6.4
 
 .. image:: https://travis-ci.org/ikreymer/pywb.png?branch=master
       :target: https://travis-ci.org/ikreymer/pywb
-.. image:: https://coveralls.io/repos/ikreymer/pywb/badge.png?branch=develop
-      :target: https://coveralls.io/r/ikreymer/pywb?branch=develop
+.. image:: https://coveralls.io/repos/ikreymer/pywb/badge.png?branch=master
+      :target: https://coveralls.io/r/ikreymer/pywb?branch=master
 .. image:: https://img.shields.io/gratipay/ikreymer.svg
       :target: https://www.gratipay.com/ikreymer/
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 pywb is a python implementation of web archival replay tools, sometimes also known as 'Wayback Machine'.
 
 pywb allows high-quality replay (browsing) of archived web data stored in standardized `ARC <http://en.wikipedia.org/wiki/ARC_(file_format)>`_ and `WARC <http://en.wikipedia.org/wiki/Web_ARChive>`_.