Update FolderBrowserDialog.xml (#9796)

Author: lonitra

xml/System.Windows.Forms/FolderBrowserDialog.xml

@@ -398,9 +398,16 @@ This class provides a way to prompt the user to browse, create, and eventually s
         <ReturnType>System.Boolean</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Gets or sets a value indicating whether the dialog box allows multiple folders to be selected.</summary>
+        <value>
+          <see langword="true" /> if the dialog box allows multiple folders to be selected together or concurrently; otherwise, <see langword="false" />. The default value is <see langword="false" />.
+        </value>
+        <remarks>
+          <format type="text/markdown"><![CDATA[  
+            Use the <xref:System.Windows.Forms.FolderBrowserDialog.SelectedPaths%2A> property to access the full list of selected folders.  
+            ]]>
+          </format>  
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="OkRequiresInteraction">
@@ -692,8 +699,8 @@ This class provides a way to prompt the user to browse, create, and eventually s
         <ReturnType>System.String[]</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
-        <value>To be added.</value>
+        <summary>Gets the paths of all selected folders in the dialog box.</summary>
+        <value>An array of folder paths for all the selected folders in the dialog box. If no folders are selected, an empty array is returned.</value>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>