Update sharepoint-site-theming-rest-api.md

updated RestRequest function and article modified date

Author: seansquires

docs/declarative-customization/site-theming/sharepoint-site-theming-rest-api.md

@@ -1,7 +1,7 @@
 ---
 title: SharePoint site theming - REST API
 description: Use the the SharePoint REST interface to perform basic create, read, update, and delete (CRUD) operations on site themes.
-ms.date: 04/19/2018
+ms.date: 0/29/2019
 localization_priority: Priority
 ---