remove credict info in export template

src/resources/export/export_template.html

@@ -38,8 +38,10 @@
     </div>
 </div>
 
+<!--
 <div class="footer" id="vnote-footer">
     <p>Generated by <em><a href="https://tamlok.github.io/vnote/">VNote</a></em>.</p>
 </div>
+-->
 </body>
 </html>