ENH: Add extra "back" button in the uploads page

Add extra "go to study description button at the bottom of the screen in
the uploads page.

Fixes qiita-spots#1754

Author: ElDeveloper

qiita_pet/templates/upload.html

@@ -59,7 +59,9 @@
     </td>
   </tr>
 </table>
-
+<div style='width:inherit;text-align:center;padding-top:30px'>
+  <small><a href="{% raw qiita_config.portal_dir %}/study/description/{{study_id}}">Go to study description</a></small>
+</div>
 
 <!-- Upload required files and JS code -->
 <script src="{% raw qiita_config.portal_dir %}/static/vendor/js/resumable.js"></script>