Correctly nest sub-menu for h3s inside h2 list item (#2345)

Author: michapietsch

package.json

@@ -2,7 +2,7 @@
   "name": "vuejs.org",
   "private": true,
   "hexo": {
-    "version": "3.8.0"
+    "version": "3.8.1"
   },
   "scripts": {
     "start": "hexo server",

themes/vue/source/js/common.js

@@ -368,12 +368,13 @@
       var headers = content.querySelectorAll('h2')
       if (headers.length) {
         each.call(headers, function (h) {
-          sectionContainer.appendChild(makeLink(h))
+          var listItem = makeLink(h)
+          sectionContainer.appendChild(listItem)
           var h3s = collectH3s(h)
           allHeaders.push(h)
           allHeaders.push.apply(allHeaders, h3s)
           if (h3s.length) {
-            sectionContainer.appendChild(makeSubLinks(h3s, isAPIOrStyleGuide))
+            listItem.appendChild(makeSubLinks(h3s, isAPIOrStyleGuide))
           }
         })
       } else {