Update CHANGELOG.md

Author: johnkil

CHANGELOG.md

@@ -8,7 +8,7 @@ _2017-02-14_
 
  * Updated roboto fonts [v2.136](https://github.com/google/roboto/releases/tag/v2.136).
  * Implemented `RobotoInflater` to apply roboto typeface for original TextView (like a [Calligraphy](https://github.com/chrisjenx/Calligraphy)).
- * Implemented gradle plugin for managing the roboto fonts.
+ * Implemented [gradle plugin](https://github.com/johnkil/Android-RobotoTextView/tree/master/robototextview-gradle-plugin) for managing the roboto fonts.
  * Refactoring of implementation: 
    - Removed deprecated class `RobotoDigitalClock`.
    - Joined of `RobotoTypefaceManager` and `RobotoTypefaceUtils` into `RobotoTypefaces`.