Update index.md

add the new control ComboBoxListItemPicker component which is related in V1.17.0

Author: PrasadKasireddy

docs/documentation/docs/index.md

@@ -49,6 +49,7 @@ The following controls are currently available:
 
 - [Carousel](./controls/Carousel) (Control displays children elements with 'previous/next element' options)
 - [Charts](./controls/ChartControl) (makes it easy to integrate [Chart.js](https://www.chartjs.org/) charts into web part)
+- [ComboBoxListItemPicker](./controls/ComboBoxListItemPicker) (allows to select one or more items from a list)
 - [DateTimePicker](./controls/DateTimePicker) (DateTime Picker)
 - [FilePicker](./controls/FilePicker) (control that allows to browse and select a file from various places)
 - [FileTypeIcon](./controls/FileTypeIcon) (Control that shows the icon of a specified file path or application)