Fix links to /docs/ in the site.

site/_includes/docs_contents.html

@@ -3,7 +3,7 @@
     <h4>Getting Started</h4>
     <ul>
       <li class="{% if page.title == "Welcome" %}current{% endif %}">
-        <a href="{{ site.url }}/docs/home">Welcome</a>
+        <a href="{{ site.url }}/docs">Welcome</a>
       </li>
       <li class="{% if page.title == "Installation" %}current{% endif %}">
         <a href="{{ site.url }}/docs/installation">Installation</a>

site/_includes/docs_contents_mobile.html

@@ -2,7 +2,7 @@
   <select onchange="if (this.value) window.location.href=this.value">
     <option value="">Navigate the docs…</option>
     <optgroup label="Getting started">
-      <option value="{{ site.url }}/docs/home">Welcome</option>
+      <option value="{{ site.url }}/docs">Welcome</option>
       <option value="{{ site.url }}/docs/installation">Installation</option>
       <option value="{{ site.url }}/docs/usage">Basic Usage</option>
       <option value="{{ site.url }}/docs/structure">Directory structure</option>

site/docs/installation.md

@@ -1,7 +1,7 @@
 ---
 layout: docs
 title: Installation
-prev_section: home
+prev_section: ""
 next_section: usage
 permalink: /docs/installation/
 ---