Update footer

For issue #26. Removes links to Mozilla and replaces them with links to addons.mozilla.org, add-ons blog, add-ons Dev Hub, Dev Policies, and forum.

_includes/footer.html

@@ -6,18 +6,14 @@
       </div>
       <section class="cell small-12 large-4 mzp-c-footer-section">
         <h4>
-          <a href="https://www.mozilla.org/">Mozilla</a>
+          <a href="https://addons.mozilla.org/">Add-ons</a>
         </h4>
         <ul>
-          <li><a href="https://www.mozilla.org/about/">About</a></li>
-          <li><a href="https://blog.mozilla.org/">Blog</a></li>
-          <li><a href="https://www.mozilla.org/contact/">Contact Us</a></li>
-          <li><a href="https://donate.mozilla.org/">Donate</a></li>
-          <li>
-            <ul class="mzp-c-footer-links-social">
-              <li><a class="twitter" href="https://twitter.com/mozilla">Twitter<span> (@mozilla)</span></a></li>
-              <li><a class="instagram" href="https://www.instagram.com/mozilla/">Instagram<span> (@mozilla)</span></a></li>
-            </ul>
+          <li><a href="https://https://addons.mozilla.org/en-US/about">About</a></li>
+          <li><a href="https://blog.mozilla.com/addons">Blog</a></li>
+          <li><a href="https://addons.mozilla.org/developers/">Developer Hub</a></li>
+	  <li><a href="https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/AMO/Policy">Developer Policies"</a></li>
+	  <li><a href="https://discourse.mozilla.org/c/add-ons">Forum"</a></li>
           </li>
         </ul>
       </section>
@@ -88,4 +84,4 @@
 	    </div>
     </nav>
   </div>
-</footer>
+</footer>