Fix social media links

Fixes #450

apps/explorer_web/lib/explorer_web/templates/layout/_footer.html.eex

@@ -1,16 +1,13 @@
 <footer class="footer">
   <div class="footer-body container">
     <div class="icon-links icon-links-primary">
-      <a href="https://www.facebook.com/PoaNetwork/" target="_blank" class="icon-link" data-toggle="tooltip" data-placement="top" title="<%= gettext("Facebook") %>">
-        <i class="fab fa-facebook-f"></i>
-      </a>
-      <a href="https://www.instagram.com/PoaNetwork/" target="_blank" class="icon-link" data-toggle="tooltip" data-placement="top" title="<%= gettext("Instagram") %>">
-        <i class="fab fa-instagram"></i>
+      <a href="https://github.com/poanetwork" target="_blank" class="icon-link" data-toggle="tooltip" data-placement="top" title="<%= gettext("Github") %>">
+        <i class="fab fa-github"></i>
       </a>
       <a href="https://www.twitter.com/PoaNetwork/" target="_blank" class="icon-link" data-toggle="tooltip" data-placement="top" title="<%= gettext("Twitter") %>">
         <i class="fab fa-twitter"></i>
       </a>
-      <a href="https://www.twitter.com/PoaNetwork/" target="_blank" class="icon-link" data-toggle="tooltip" data-placement="top" title="<%= gettext("Telegram") %>">
+      <a href="http://t.me/oraclesnetwork" target="_blank" class="icon-link" data-toggle="tooltip" data-placement="top" title="<%= gettext("Telegram") %>">
         <i class="fab fa-telegram-plane"></i>
       </a>
     </div>