feat(vue/button): Add onClick callback to showcase

Author: Brayan-724

js/vue/lib/components/rs-button.showcase.vue

@@ -8,6 +8,7 @@ const props = {
     default: "primary",
     options: ["primary", "secondary", "text", "icon"],
   },
+  onClick: "callback"
 };
 const slots = {
   default: {