update docs

closes #2383

Author: kazupon

themes/vue/_config.yml

@@ -2,6 +2,11 @@ site_description: Vue.js - The Progressive JavaScript Framework
 google_analytics: UA-46852172-1
 root_domain: jp.vuejs.org
 vue_version: 2.5.16
+special_sponsors:
+  - url: 'https://www.dcloud.io/hbuilderx.html?hmsr=vue-en&hmpl=&hmcu=&hmkw=&hmci='
+    img: hbuilder.png
+    name: HBuilder
+    description: An IDE for Vue
 platinum_sponsors_china:
   - url: 'http://www.dcloud.io/?hmsr=vuejsorg&hmpl=&hmcu=&hmkw=&hmci='
     img: dcloud.gif

themes/vue/source/css/index.styl

@@ -123,7 +123,7 @@ body
     display: inline-block
     vertical-align: middle
   img
-    margin: 15px
+    margin: 15px 0 0
 
 #highlights
   background-color: #fff