fix help modal button URL

lms/templates/help_modal.html

@@ -51,7 +51,7 @@
     <p>${_('Have <strong>general questions about {platform_name}</strong>? You can find lots of helpful information in the {platform_name} Help Center.').format(platform_name=platform_name)}</p>
 	
 	<div class="help-buttons">
-	  <a id="help-center-button" href="{url}" target="_blank">
+	  <a id="help-center-button" href="http://stanfordonline.zendesk.com/hc" target="_blank">
 		${_('Access the Help Center')}
 	  </a>
 	</div>