message: Link to /about in main header bar
diff: </a>
  <ul class="pure-menu-list">
  + <li class="pure-menu-item">
  + <a href="/about" class="pure-menu-link">
  + About
  + </a>
  + </li>
  +
  <li class="pure-menu-item">
  <a href="/releases" class="pure-menu-link">
  Releases
  The Cargo Guide
  </a>
  </li>
  -
  - <li class="pure-menu-item">
  - <a href="/about" class="pure-menu-link">
  - About Docs.rs
  - </a>
  - </li>
  </ul>
  </li>
  