SelectBox: Update Overview demo description (#31057)

Author: arman-boyakhchyan

apps/demos/Demos/SelectBox/Overview/React/description.md

@@ -0,0 +1,21 @@
+The [SelectBox](/Documentation/ApiReference/UI_Components/dxSelectBox/) component allows users to select an item from a drop-down list.
+<!--split-->
+
+This demo illustrates the following SelectBox properties:
+
+- [items](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#items)    
+Specifies an array of items displayed in the SelectBox.
+- [placeholder](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#placeholder)       
+Specifies the text that is displayed when no items are selected.
+- [readOnly](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#readOnly)     
+Prevents users from changing the editor's value via the UI.
+- [disabled](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#disabled)        
+Specifies whether the SelectBox responds to user interaction.
+- [dataSource](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#dataSource)        
+Binds the SelectBox to data. Unlike the **items** property, **dataSource** accepts the [DataSource](/Documentation/ApiReference/Data_Layer/DataSource/) object that allows users to sort, filter, group, and shape data.
+- **fieldAddons**.[beforeRender](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/fieldAddons/#beforeRender) and [itemRender](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#itemRender)       
+Allow you to customize the text field and drop-down list items.
+- [onValueChanged](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#onValueChanged) event handler      
+Use this function to perform an action when a user chooses a new value. In this demo, this function is used to display the selected value.
+
+To get started with the DevExtreme SelectBox component, refer to the following tutorial for step-by-step instructions: [Getting Started with SelectBox](/Documentation/Guide/UI_Components/SelectBox/Getting_Started_with_SelectBox/).

apps/demos/Demos/SelectBox/Overview/ReactJs/description.md

@@ -0,0 +1,21 @@
+The [SelectBox](/Documentation/ApiReference/UI_Components/dxSelectBox/) component allows users to select an item from a drop-down list.
+<!--split-->
+
+This demo illustrates the following SelectBox properties:
+
+- [items](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#items)    
+Specifies an array of items displayed in the SelectBox.
+- [placeholder](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#placeholder)       
+Specifies the text that is displayed when no items are selected.
+- [readOnly](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#readOnly)     
+Prevents users from changing the editor's value via the UI.
+- [disabled](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#disabled)        
+Specifies whether the SelectBox responds to user interaction.
+- [dataSource](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#dataSource)        
+Binds the SelectBox to data. Unlike the **items** property, **dataSource** accepts the [DataSource](/Documentation/ApiReference/Data_Layer/DataSource/) object that allows users to sort, filter, group, and shape data.
+- **fieldAddons**.[beforeRender](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/fieldAddons/#beforeRender) and [itemRender](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#itemRender)       
+Allow you to customize the text field and drop-down list items.
+- [onValueChanged](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#onValueChanged) event handler      
+Use this function to perform an action when a user chooses a new value. In this demo, this function is used to display the selected value.
+
+To get started with the DevExtreme SelectBox component, refer to the following tutorial for step-by-step instructions: [Getting Started with SelectBox](/Documentation/Guide/UI_Components/SelectBox/Getting_Started_with_SelectBox/).

apps/demos/Demos/SelectBox/Overview/description.md

@@ -1,7 +1,7 @@
 The [SelectBox](/Documentation/ApiReference/UI_Components/dxSelectBox/) component allows users to select an item from a drop-down list.
 <!--split-->
 
-This demo illustrates the following  SelectBox properties:
+This demo illustrates the following SelectBox properties:
 
 - [items](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#items)    
 Specifies an array of items displayed in the SelectBox.
@@ -13,7 +13,7 @@ Prevents users from changing the editor's value via the UI.
 Specifies whether the SelectBox responds to user interaction.
 - [dataSource](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#dataSource)        
 Binds the SelectBox to data. Unlike the **items** property, **dataSource** accepts the [DataSource](/Documentation/ApiReference/Data_Layer/DataSource/) object that allows users to sort, filter, group, and shape data.
-- [fieldTemplate](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#fieldTemplate) and [itemTemplate](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#itemTemplate)       
+- **fieldAddons**.[beforeTemplate](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/fieldAddons/#beforeTemplate) and [itemTemplate](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#itemTemplate)       
 Allow you to customize the text field and drop-down list items.
 - [onValueChanged](/Documentation/ApiReference/UI_Components/dxSelectBox/Configuration/#onValueChanged) event handler      
 Use this function to perform an action when a user chooses a new value. In this demo, this function is used to display the selected value.