chore: remove vueschool banner (#982)

Author: rahaug

src/.vuepress/config.js

@@ -458,8 +458,7 @@ module.exports = {
       carbon: 'CEBDT27Y',
       custom: 'CKYD62QM',
       placement: 'vuejsorg'
-    },
-    topBanner: true
+    }
   },
   plugins: [
     [