[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/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 %}