fix star button

Author: yyx990803

themes/vue/layout/index.ejs

@@ -18,7 +18,7 @@
     </p>
     <ul id="social">
       <li><a href="https://twitter.com/vuejs" class="twitter-follow-button" data-show-count="false" data-dnt="true">Follow @vuejs</a></li>
-      <li><iframe src="http://ghbtns.com/github-btn.html?user=yyx990803&repo=vue&type=watch&count=true"
+      <li><iframe src="http://ghbtns.com/github-btn.html?user=vuejs&repo=vue&type=watch&count=true"
     allowtransparency="true" frameborder="0" scrolling="0" width="100" height="20"></iframe></li>
     </ul>
     <ul id="translations">