[Docs] Force using current protocol scheme for resources and links

If the docs is accessed with https, change all links to be https as well.

docs/_includes/head.html

@@ -6,7 +6,7 @@
   <title>{% if page.title %}{{ page.title | escape }}{% else %}{{ site.title | escape }}{% endif %}</title>
   <meta name="description" content="{% if page.excerpt %}{{ page.excerpt | strip_html | strip_newlines | truncate: 160 }}{% else %}{{ site.description }}{% endif %}">
 
-  <link rel="stylesheet" href="{{ "/css/main.css" | prepend: site.github.url }}">
+  <link rel="stylesheet" href="{{ "/css/main.css" | prepend: site_url }}">
   {% if site.algolia.enabled %}
   <link rel="stylesheet" href="//cdn.jsdelivr.net/docsearch.js/1/docsearch.min.css" />
   {% endif %}

docs/_includes/header.html

@@ -1,7 +1,7 @@
 <header class="site-header">
 
   <div class="wrapper">
-    <a class="site-title" href="{{ site.github.url }}/">{{ site.title }}</a>
+    <a class="site-title" href="{{ site_url }}/">{{ site.title }}</a>
 
     <nav class="site-nav">
       <a href="#" class="menu-icon">
@@ -12,10 +12,10 @@
         </svg>
       </a>
       <div class="trigger">
-        <a class="page-link" href="{{ site.github.url }}/getting-started/">Getting Started</a>
-        <a class="page-link" href="{{ site.github.url }}/docs/">Documentation</a>
-        <a class="page-link" href="{{ site.github.url }}/guides/">Guides</a>
-        <a class="page-link" href="{{ site.github.url }}/faq/">FAQ</a>
+        <a class="page-link" href="{{ site_url }}/getting-started/">Getting Started</a>
+        <a class="page-link" href="{{ site_url }}/docs/">Documentation</a>
+        <a class="page-link" href="{{ site_url }}/guides/">Guides</a>
+        <a class="page-link" href="{{ site_url }}/faq/">FAQ</a>
         <a class="page-link" href="{{ site.github.repository_url }}">
             <span class="icon icon--github">{% include icon-github.svg %}</span>
             <span class="username">GitHub</span>

docs/_includes/section-why-use-spout.html

@@ -13,7 +13,7 @@
         <li class="feature-check">{{ site.spout_html }}'s API is {{emS}}developer-friendly{{emE}}.</li>
     </ul><br>
     <div class="btn-wrapper">
-        <a href="{{ site.github.url }}/getting-started/" class="page-link"><button class="btn">Get started</button></a>
+        <a href="{{ site_url }}/getting-started/" class="page-link"><button class="btn">Get started</button></a>
     </div>
 {% endcapture %}
 

docs/_includes/section.html

@@ -9,7 +9,7 @@
       {% assign sectionIconsAsArray = sectionIcons | split:'~~' %}
       <div class="icons">
       {% for icon in sectionIconsAsArray %}
-        <img src="{{ site.github.url }}/images/{{ icon }}"/>
+        <img src="{{ site_url }}/images/{{ icon }}"/>
       {% endfor %}
       </div>
     {% endif %}