update checkbox text

Signed-off-by: Sahil Yeole <sahilyeole93@gmail.com>

flutter/lib/desktop/pages/desktop_setting_page.dart

@@ -331,7 +331,7 @@ class _GeneralState extends State<_General> {
           'allow-always-software-render'),
     ));
      children.add(
-        _OptionCheckBox(context, 'Check for software update on startup.','enable-check-update',
+        _OptionCheckBox(context, 'Check for software update on startup','enable-check-update',
         isServer: false,
     ));
     if (bind.mainShowOption(key: 'allow-linux-headless')) {