add docs callout to mention twbs#9947

css.html

@@ -757,6 +757,10 @@ <h3>Emphasis classes</h3>
 <p class="text-warning">...</p>
 <p class="text-danger">...</p>
 {% endhighlight %}
+    <div class="bs-callout bs-callout-info">
+      <h4>Dealing with specificity</h4>
+      <p>Sometimes emphasis classes cannot be applied due to the specificity of another selector. In most cases a sufficient workaround is to wrap your text in a <code>&gt;span&lt;</code> with the class.</p>
+    </div>
 
 
     <!-- Abbreviations -->