add note for icon class usage per #1501

docs/base-css.html

@@ -1469,6 +1469,10 @@ For example, <code>section</code> should be wrapped as inline.
 <i class="icon-search icon-white"></i>
 </pre>
       <p>There are 120 classes to choose from for your icons. Just add an <code>&lt;i&gt;</code> tag with the right classes and you're set. You can find the full list in <strong>sprites.less</strong> or right here in this document.</p>
+      <div class="alert alert-info">
+        <strong>Heads up!</strong>
+        The <code>.icon-</code> class must be listed first in the class tag for proper CSS targeting.
+      </div>
     </div>
     <div class="span4">
       <h3>Use cases</h3>

docs/templates/pages/base-css.mustache

@@ -1393,6 +1393,10 @@
 <i class="icon-search icon-white"></i>
 </pre>
       <p>{{_i}}There are 120 classes to choose from for your icons. Just add an <code>&lt;i&gt;</code> tag with the right classes and you're set. You can find the full list in <strong>sprites.less</strong> or right here in this document.{{/i}}</p>
+      <div class="alert alert-info">
+        <strong>{{_i}}Heads up!{{/i}}</strong>
+        {{_i}}The <code>.icon-</code> class must be listed first in the class tag for proper CSS targeting.{{/i}}
+      </div>
     </div>
     <div class="span4">
       <h3>{{_i}}Use cases{{/i}}</h3>