Update working-with-folders-and-files-with-rest.md (SharePoint#5930)

Correct Typo

Author: PrasadKasireddy

docs/sp-add-ins/working-with-folders-and-files-with-rest.md

@@ -168,7 +168,7 @@ static void Main(string[] args)
     }
     ICredentials credentials = new SharePointOnlineCredentials("xxxxxx.onmicrosoft.com", secureString);
 
-    //set credential of SharePoint 2013(on-premise)
+    //set credential of SharePoint 2013(On-Premises)
     //string userName = "Administrator";
     //string password = "xxxxxxx";
     //string ___domain = "CONTOSO";