add Changelog link in update help card (#13997)

Signed-off-by: 21pages <sunboeasy@gmail.com>

flutter/lib/desktop/pages/desktop_home_page.dart

@@ -450,7 +450,11 @@ class _DesktopHomePageState extends State<DesktopHomePage>
           "${translate("new-version-of-{${bind.mainGetAppNameSync()}}-tip")} (${bind.mainGetNewVersion()}).",
           btnText,
           onPressed,
-          closeButton: true);
+          closeButton: true,
+          help: isToUpdate ? 'Changelog' : null,
+          link: isToUpdate
+              ? 'https://github.com/rustdesk/rustdesk/releases/tag/${bind.mainGetNewVersion()}'
+              : null);
     }
     if (systemError.isNotEmpty) {
       return buildInstallCard("", systemError, "", () {});