added api reference

Author: subash-sf

README.md

@@ -2,7 +2,7 @@
 
 JSON is one of the most widely used data formats, but working with it can be challenging.
 
-This article focuses on extracting data from JSON files and visualizing it using bar charts, line charts, and pie charts from the Syncfusion WPF Charts control.
+This article focuses on extracting data from JSON files and visualizing it using bar charts, line charts, and pie charts from the [Syncfusion WPF Charts](https://help.syncfusion.com/wpf/charts/getting-started) control.
 
 Four easy steps can be used to quickly display data from a JSON web service using the WPF Charts simplicity:
 1.	Retrieve the data from json string or web service using HttpClient.