udpate vue-devtools url

Author: yyx990803

src/.vitepress/config.js

@@ -79,7 +79,7 @@ module.exports = {
               },
               {
                 text: 'Devtools',
-                link: 'https://github.com/vuejs/vue-devtools'
+                link: 'https://devtools.vuejs.org'
               }
             ]
           }