fix the vue-router.js cdn url (vuejs#1001)

Author: xalexec

docs/en/essentials/getting-started.md

@@ -10,7 +10,7 @@ Creating a Single-page Application with Vue.js + vue-router is dead simple. With
 
 ``` html
 <script src="https://unpkg.com/vue/dist/vue.js"></script>
-<script src="https://unpkg.com/vue-router"></script>
+<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>
 
 <div id="app">
   <h1>Hello App!</h1>

docs/ja/essentials/getting-started.md

@@ -10,7 +10,7 @@ Vue.js と vue-router を使ったシングルページアプリケーション
 
 ``` html
 <script src="https://unpkg.com/vue/dist/vue.js"></script>
-<script src="https://unpkg.com/vue-router"></script>
+<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>
 
 <div id="app">
   <h1>Hello App!</h1>

docs/ru/essentials/getting-started.md

@@ -10,7 +10,7 @@
 
 ``` html
 <script src="https://unpkg.com/vue/dist/vue.js"></script>
-<script src="https://unpkg.com/vue-router"></script>
+<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>
 
 <div id="app">
   <h1>Hello App!</h1>

docs/zh-cn/essentials/getting-started.md

@@ -8,7 +8,7 @@
 
 ``` html
 <script src="https://unpkg.com/vue/dist/vue.js"></script>
-<script src="https://unpkg.com/vue-router"></script>
+<script src="https://unpkg.com/vue-router/dist/vue-router.js"></script>
 
 <div id="app">
   <h1>Hello App!</h1>