https://github.com/twitter/bootstrap/pull/6342 icons section
mentions the change to using glyphicon base class
this adds it to the docs
{% endhighlight %}
<div class="bs-callout bs-callout-info">
<h4>Glyphicon Alternative</h4>
- <p>With <a href="/css/#glyphicons">Glyphicons</a> available, you may choose to style the left and right toggle buttons with <code>.glyphicon-chevron-left</code> and <code>.glyphicon-chevron-right</code>.</p>
+ <p>With <a href="/css/#glyphicons">Glyphicons</a> available, you may choose to style the left and right toggle buttons with <code>.glyphicon .glyphicon-chevron-left</code> and <code>.glyphicon .glyphicon-chevron-right</code>.</p>
</div>
<h3>Optional captions</h3>