docs(grid): updated demo link

Author: svdimitr

components/grid/columns/virtual.md

@@ -312,7 +312,7 @@ Column virtualization is commonly used when you have many columns. You may not h
 
 
 ## See also
- * [Live demo: Virtual Columns](https://demos.telerik.com/blazor-ui/grid/virtual-columns)
+ * [Live demo: Virtual Columns](https://demos.telerik.com/blazor-ui/grid/column-virtualization)
  * [Virtual Scrolling]({%slug components/grid/virtual-scrolling%})
  * [Grid Column Width Behavior]({%slug grid-columns-width%})
  * [Automatically Generated Columns]({%slug grid-columns-automatically-generated%})