update demo link

Author: yyx990803

README.md

@@ -3,7 +3,7 @@
 HackerNews clone built with Vue 2.0 + vue-router + vuex, with server-side rendering.
 
 <p align="center">
-  <a href="https://vue-hn.now.sh" target="_blank">
+  <a href="https://vue-hn.herokuapp.com" target="_blank">
     <img src="https://cloud.githubusercontent.com/assets/499550/17546273/5aabc5fc-5eaf-11e6-8d6a-ad00937e8bd6.png" width="700px">
     <br>
     Live Demo