feat(footer): add github link

hiroppy · kt3k · commit d98ee0b8a978 · 2017-04-08T12:22:50.000+09:00
diff --git a/source/layout/layout.njk b/source/layout/layout.njk
@@ -25,7 +25,10 @@
 
 <hr/>
 <footer>
-<p><small>© 2016 {{ orgName }}</small></p>
+<p>
+  <small>© 2016 {{ orgName }}</small>
+  <small><a href="https://github.com/nodejsjp/nodejsjp.github.com">GitHub</a></small>
+</p>
 </footer>
 </section>
 <script type="text/javascript">
