Remove "updated on" from jinja template

Regenerating docs was creating big messy commits even for simple changes due to 470+ trivial one-line changes in timestamps across the files. Dropping the Updated On line makes it easier to track actual changes in the documentation.

Author: jeremydouglass

templates/reference_item_template.jinja

@@ -73,5 +73,4 @@
     {% endif %}
 </table>
 
-Updated on {{ today }}.
 {% endblock %}