fix(README): Update link for 2.x code

fix #6747

Author: mportuga

README.md

@@ -164,7 +164,7 @@ The full list of SauceLabs browsers can be seen by running `grunt saucebrowsers`
 
 # What Happened to 2.x?
 
-As of the 3.0 release, 2.x is officially deprecated. There will be no further releases. If for some reason you need to find the 2.x source please see the [2.x branch](https://github.com/angular-ui/ui-grid/tree/2.x).
+As of the 3.0 release, 2.x is officially deprecated. There will be no further releases. If for some reason you need to find the 2.x source please see the [2.x branch](https://github.com/angular-ui/ng-grid-legacy).
 
 The 2.x docs are here: [http://angular-ui.github.io/ui-grid/](http://angular-ui.github.io/ui-grid/).