Add docker install URL for 28.0

Author: eva-vashkevich

lib/shared/addon/components/form-engine-opts/component.js

@@ -47,6 +47,10 @@ export default Component.extend({
     } catch (_err) {}
 
     let out           = [
+      {
+        label: 'v28.0.x',
+        value: 'https://releases.rancher.com/install-docker/28.0.sh'
+      },
       {
         label: 'v27.5.x',
         value: 'https://releases.rancher.com/install-docker/27.5.sh'