fixes #4556: add mention of disable state and required js to buttons docs

docs/base-css.html

@@ -1558,7 +1558,7 @@ For example, <code><section></code> should be wrapped as inlin
 </pre>
           <p>
             <span class="label label-info">Heads up!</span>
-            We use <code>.disabled</code> as a utility class here, similar to the common <code>.active</code> class, so no prefix is required.
+            We use <code>.disabled</code> as a utility class here, similar to the common <code>.active</code> class, so no prefix is required. Also, this class is only for aesthetic; you must use custom JavaScript to disable links here.
           </p>
 
           <h3>Button element</h3>

docs/templates/pages/base-css.mustache

@@ -1495,7 +1495,7 @@
 </pre>
           <p>
             <span class="label label-info">{{_i}}Heads up!{{/i}}</span>
-            {{_i}}We use <code>.disabled</code> as a utility class here, similar to the common <code>.active</code> class, so no prefix is required.{{/i}}
+            {{_i}}We use <code>.disabled</code> as a utility class here, similar to the common <code>.active</code> class, so no prefix is required. Also, this class is only for aesthetic; you must use custom JavaScript to disable links here.{{/i}}
           </p>
 
           <h3>Button element</h3>