add documentation links

Author: geumjaLee

Readme.md

@@ -39,4 +39,11 @@ This sample introduces API properties and methods used to perform the following
 ## More Examples
 
 * [WPF SpreadsheetControl API - Part 1](https://github.com/DevExpress-Examples/wpf-spreadsheetcontrol-api-part-1)
-* [WPF SpreadsheetControl API - Part 3](https://github.com/DevExpress-Examples/wpf-spreadsheetcontrol-api-part-3)
+* [WPF SpreadsheetControl API - Part 3](https://github.com/DevExpress-Examples/wpf-spreadsheetcontrol-api-part-3)
+
+## Documentation
+
+* [Pictures in Spreadsheet Documents](https://docs.devexpress.com/WPF/400492/controls-and-libraries/spreadsheet/charts-and-graphics/pictures)
+* [Spreadsheet for WPF Examples](https://docs.devexpress.com/WPF/16123/controls-and-libraries/spreadsheet/examples)
+* [Sort Data in Spreadsheet for WPF](https://docs.devexpress.com/WPF/17471/controls-and-libraries/spreadsheet/data-presentation/sorting)
+* [Filter Data in Spreadsheet for WPF](https://docs.devexpress.com/WPF/18162/controls-and-libraries/spreadsheet/data-presentation/filtering)