Adds code of conduct link to the footer

Author: zachleat

src/site/_includes/footer.njk

@@ -5,6 +5,7 @@
       <li class="p-2"><a href="https://jamstack.org/slack">Chat on Slack</a></li>
       <li class="p-2"><a href="https://community.netlify.com/">Netlify Support</a></li>
       <li class="p-2"><a href="{{ pkg.repository.url }}">Code on GitHub</a></li>
+      <li class="p-2"><a href="/code-of-conduct/">Code of Conduct</a></li>
     </ul>
   </footer>
 </section>