add line item to docs on upgrading per #1488

docs/templates/pages/upgrading.mustache

@@ -128,6 +128,7 @@
   <ul>
     <li>{{_i}}Updated the <code>.dropdown-menu</code> to tighten up spacing{{/i}}</li>
     <li>{{_i}}Now requires you to add a <code>&lt;span class="caret"&gt;&lt;/span&gt;</code> to show the dropdown arrow{{/i}}</li>
+    <li>{{_i}}Now requires you to add a <code>data-toggle="dropdown"</code> attribute to obtain toggling behavior{{/i}}</li>
     <li>{{_i}}The navbar (fixed topbar) has brand new dropdowns. Gone are the dark versions and in their place are the standard white ones with an additional caret at their tops for clarity of position.{{/i}}</li>
   </ul>
   <h3>{{_i}}Labels{{/i}}</h3>

docs/upgrading.html

@@ -204,6 +204,7 @@
   <ul>
     <li>Updated the <code>.dropdown-menu</code> to tighten up spacing</li>
     <li>Now requires you to add a <code>&lt;span class="caret"&gt;&lt;/span&gt;</code> to show the dropdown arrow</li>
+    <li>Now requires you to add a <code>data-toggle="dropdown"</code> attribute to obtain toggling behavior</li>
     <li>The navbar (fixed topbar) has brand new dropdowns. Gone are the dark versions and in their place are the standard white ones with an additional caret at their tops for clarity of position.</li>
   </ul>
   <h3>Labels</h3>