Fix documentation reference to WinSW source code

Update comment to reference the actual source code location of the
elevation check rather than the extensions documentation page which
does not document the /elevated flag.

Author: Aditya

core/src/main/java/hudson/lifecycle/WindowsServiceLifecycle.java

@@ -145,7 +145,7 @@ public void restart() throws IOException, InterruptedException {
         // use restart! to run hudson/jenkins.exe restart in a separate process, so it doesn't kill itself
         // Pass /elevated to skip WinSW's elevation check when the service ACL grants sufficient permissions
         // This allows Jenkins running as a limited user to restart when proper service permissions are configured
-        // See: https://github.com/winsw/winsw/blob/master/docs/extensions.md
+        // See: https://github.com/winsw/winsw/blob/ee29eee8cf98864b786c9b5e6bd6f6ce351b85a3/src/Core/ServiceWrapper/Main.cs#L911-L916
         int r = new LocalLauncher(task).launch().cmds(executable, "/elevated", "restart!")
                 .stdout(task).pwd(home).join();
         if (r != 0)