chore: remove unused files, disable dev tip

Author: yyx990803

docs/.vuepress/components/Foo.vue

@@ -21,14 +21,12 @@ if (module.hot) {
   })
 }
 
+Vue.config.productionTip = false
 Vue.use(Router)
-
 // mixin for exposing $site and $page
 Vue.mixin(dataMixin)
-
 // component for rendering markdown content and setting title etc.
 Vue.component('Content', Content)
-
 // component for client-only content
 Vue.component('ClientOnly', ClientOnly)