Update docs badge in README

Update the URL of the docs badge to include it from inch-ci.org instead of inch-pages.github.io (the former being the successor of the Inch Pages project).

[ci skip]

README.md

 Paperclip
 =========
 
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+[![Build Status](https://secure.travis-ci.org/thoughtbot/paperclip.png?branch=master)](http://travis-ci.org/thoughtbot/paperclip) [![Dependency Status](https://gemnasium.com/thoughtbot/paperclip.png?travis)](https://gemnasium.com/thoughtbot/paperclip) [![Code Climate](https://codeclimate.com/github/thoughtbot/paperclip.png)](https://codeclimate.com/github/thoughtbot/paperclip) [![Inline docs](http://inch-ci.org/github/thoughtbot/paperclip.png)](http://inch-ci.org/github/thoughtbot/paperclip)
 
 Paperclip is intended as an easy file attachment library for Active Record. The
 intent behind it was to keep setup as easy as possible and to treat files as