Docs: Add missing property

Change-Id: I1f4a0602f23cba86adbf627b0881ae5034db0af8
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/98188
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>

offapi/com/sun/star/sheet/DocumentSettings.idl

@@ -108,6 +108,10 @@ published service DocumentSettings
         grid settings in the user interface.
      */
     [optional, property] boolean IsRasterAxisSynchronized;
+
+    /** enables the document sharing feature (Tools->Share Spreadsheet)
+     */
+    [optional, property] boolean IsDocumentShared;
 };