minor #2225 Fixed the invalid link in Readme.md. (mzk)

This PR was merged into the 3.0-dev branch.

Discussion
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Fixed the invalid link in Readme.md.

Fixed the invalid link in Readme.md.

Commits
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5029561 Fixed the invalid link in Readme.md.

Author: xabbuh

README.md

@@ -27,7 +27,7 @@ Documentation
 
 [Read the Documentation](http://symfony.com/doc/master/bundles/FOSRestBundle/index.html)
 
-Please see the [UPGRADING-2.0.md](https://github.com/FriendsOfSymfony/FOSRestBundle/blob/master/UPGRADING-2.0.md) for any
+Please see the [UPGRADING-3.0.md](https://github.com/FriendsOfSymfony/FOSRestBundle/blob/master/UPGRADING-3.0.md) for any
 relevant instructions when upgrading to a newer version.
 
 Installation