add links to repository

Author: baillma3

index.md

@@ -1,9 +1,8 @@
-## Welcome to the graphics principles cheat sheet landing page. 
+## Graphics principles cheat sheet
 
-This the landing page for the [cheatsheet](https://github.com/GraphicsPrinciples/CheatSheet/blob/master/NVSCheatSheet.pdf). 
- 
+This the landing page for the [cheatsheet](https://github.com/GraphicsPrinciples/CheatSheet/blob/master/NVSCheatSheet.pdf). You can access the [cheatsheet on GitHub](https://github.com/GraphicsPrinciples/CheatSheet/blob/master/NVSCheatSheet.pdf). 
 
-You can access the [cheatsheet on GitHub](https://github.com/GraphicsPrinciples/CheatSheet/blob/master/NVSCheatSheet.pdf). 
+The [R code](https://github.com/GraphicsPrinciples/CheatSheet) is also available for many of the examples. This can be access [here](https://github.com/GraphicsPrinciples/CheatSheet)