Properly link the fixed issue

Author: MadLittleMods

CHANGELOG.md

@@ -1,7 +1,7 @@
 
 # v0.5.1 - 2015-10-24
 
- - Fix postcss/postcss#611 where we were trying to remove the root node on clean up
+ - Fix [postcss/postcss#611](https://github.com/postcss/postcss/issues/611) where we were trying to remove the root node on clean up
  - Improved test setup
 
 # v0.5.0 - 2015-9-12