Add a link to elixir meetups around the world

Author: José Valim

_includes/important-links.html

@@ -2,6 +2,7 @@
   <h3 class="widget-title">Join the Community</h3>
   <ul>
     <li><a class="spec" href="irc://irc.freenode.net/elixir-lang">#elixir-lang on freenode IRC</a></li>
+    <li><a class="spec" href="http://elixir.meetup.com">Elixir meetups around the world</a></li>
     <li><a class="spec" href="http://groups.google.com/group/elixir-lang-talk">elixir-talk mailing list (questions)</a></li>
     <li><a class="spec" href="http://groups.google.com/group/elixir-lang-core">elixir-core mailing list (development)</a></li>
     <li><a class="spec" href="https://github.com/elixir-lang/elixir/issues">Issue tracker</a></li>