Fix tab order

We only have a small number of tabs, which is not really dynamic and we want it in a fixed order which is not alphabetic.

_includes/header.html

@@ -14,11 +14,9 @@
       </a>
 
       <div class="trigger">
-        {% for my_page in site.pages %}
-          {% if my_page.title %}
-          <a class="page-link" href="{{ my_page.url | prepend: site.baseurl }}">{{ my_page.title }}</a>
-          {% endif %}
-        {% endfor %}
+        <a class="page-link" href="{{ site.baseurl }}">Home</a>
+        <a class="page-link" href="{{ site.baseurl }}installation/">Installation</a>
+        <a class="page-link" href="{{ site.baseurl }}about/">About</a>
       </div>
     </nav>