Update README.md

Author: furkanaskin

README.md

@@ -47,7 +47,7 @@ To setup with legend you need an root layout for legend.
 ```kotlin
 chart.showLegend(legendLayout)
 ```
-Or use with custom legend adapter by inheriting from LegendAdapter
+Or use with custom legend adapter by inheriting from [LegendAdapter](https://github.com/furkanaskin/ClickablePieChart/blob/master/lib/src/main/java/com/faskn/lib/legend/LegendAdapter.kt)
 ```kotlin
 chart.showLegend(legendLayout, CustomLegendAdapter())
 ```