move to separate about page

_includes/nav-about.html

@@ -0,0 +1,9 @@
+<li>
+  <a href="#history">History</a>
+</li>
+<li>
+  <a href="#team">Core team</a>
+</li>
+<li>
+  <a href="#community">Community</a>
+</li>

_includes/nav-main.html

@@ -27,6 +27,11 @@
           <a href="{{ page.base_url }}customize">Customize</a>
         </li>
       </ul>
+      <ul class="nav navbar-nav navbar-right">
+        <li{% if page.slug == "about" %} class="active"{% endif %}>
+          <a href="{{ page.base_url }}about">About</a>
+        </li>
+      </ul>
     </nav>
   </div>
 </header>