Update documentation to reference new server side sorting functionality.

site/docs/extensions/filter-control.md

@@ -202,7 +202,7 @@ Dependence if you use the datepicker option: [bootstrap-datepicker](https://gith
 
 - **Detail:**
 
-   Set this to order the options in a select control whether ascending or descending.
+   Set this to order the options in a select control whether ascending (`'asc'`), descending (`'desc'`) or in the order provided by the server (`'server'`).
 
 - **Default:** `'asc'`