use getbootstrap for tweet button

_includes/social-buttons.html

@@ -10,7 +10,7 @@
       <a href="https://twitter.com/twbootstrap" class="twitter-follow-button" data-link-color="#0069D6" data-show-count="true">Follow @twbootstrap</a>
     </li>
     <li class="tweet-btn">
-      <a href="https://twitter.com/share" class="twitter-share-button" data-url="http://twbs.github.com/bootstrap/" data-count="horizontal" data-via="twbootstrap" data-related="mdo:Creator of Twitter Bootstrap">Tweet</a>
+      <a href="https://twitter.com/share" class="twitter-share-button" data-url="http://getbootstrap.com/" data-count="horizontal" data-via="twbootstrap" data-related="mdo:Creator of Twitter Bootstrap">Tweet</a>
     </li>
   </ul>
 </div>