docs: change some http links to https

.editorconfig

@@ -1,4 +1,4 @@
-# http://editorconfig.org
+# https://editorconfig.org
 root = true
 
 [*]

mock/mock-server.js

@@ -29,7 +29,7 @@ module.exports = app => {
   require('@babel/register')
 
   // parse app.body
-  // http://expressjs.com/en/4x/api.html#req.body
+  // https://expressjs.com/en/4x/api.html#req.body
   app.use(bodyParser.json())
   app.use(bodyParser.urlencoded({
     extended: true

src/views/components-demo/splitpane.vue

@@ -1,7 +1,7 @@
 <template>
   <div class="components-container">
     <code><strong>SplitPane</strong> If you've used
-      <a href="http://codepen.io/" target="_blank"> codepen</a>,
+      <a href="https://codepen.io/" target="_blank"> codepen</a>,
       <a href="https://jsfiddle.net/" target="_blank"> jsfiddle </a>will not be unfamiliar.
       <a href="https://github.com/PanJiaChen/vue-split-pane" target="_blank"> Github repository</a>
     </code>