replace github mirror with new developers guide

i2p2www/pages/global/footer.html

@@ -11,7 +11,7 @@
     <li><a href="{{ site_url('contact') }}"><div class="footeritem"><span>{{ _('Contact us') }}</span></div></a></li>
     <li><a href="http://{{ i2pconv('i2pforum.i2p') }}/"><div class="footeritem"><span>{{ _('Forums') }}</span></div></a></li>
     <li><a href="https://reddit.com/r/i2p"><div class="footeritem"><span>Reddit</span></div></a></li>
-    <li><a href="https://github.com/i2p"><div class="footeritem"><span>Github(Mirror)</span></div></a></li>
+    <li><a href="{{ site_url('get-involved/guides/new-developers') }}"><div class="footeritem"><span>Develop</span></div></a></li>
   </ul>
 </div>
 <div id="footermenu" class="third">