docs - add history page; add return codes manual page

license.html

@@ -79,6 +79,7 @@
 <li><a href="index.html">Home</a></li>
 <li><a href="downloads.html">Downloads</a></li>
 <li><a href="docs/index.html">Documentation</a></li>
+<li><a href="history.html">History</a></li>
 <li><a href="https://git.montaukos.org/daniel/MontaukOS/issues">Issue tracker</a></li>
 <li><a href="https://git.montaukos.org/daniel/MontaukOS">Git</a></li>
 </ul>