fix(vuetify): output css file

Author: abichinger

docs/src/guide/getting-started.md

@@ -24,6 +24,7 @@ Then you need to register `vue-js-cron/vuetify` with `Vue.use()`
 
 ```js
 import cronVuetify from '@vue-js-cron/vuetify'
+import '@vue-js-cron/vuetify/dist/vuetify.css'
 Vue.use(cronVuetify)
 ```
 

vuetify/build/rollup.config.js

@@ -9,7 +9,9 @@ export default {
         exports: 'named',
     },
     plugins: [
-        css(),
+        css({
+            output: 'vuetify.css',
+        }),
         vue({
             css: false, // Dynamically inject css as a <style> tag
             compileTemplate: true, // Explicitly convert template to render function