add heads up label to new docs mention

docs/base-css.html

@@ -1537,7 +1537,10 @@ 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>
-      <p>When using beside strings of text, as in buttons or nav links, be sure to leave a space after the <code>&lt;i&gt;</code> tag for proper spacing.</p>
+      <p>
+        <span class="label label-info">Heads up!</span>
+        When using beside strings of text, as in buttons or nav links, be sure to leave a space after the <code>&lt;i&gt;</code> tag for proper spacing.
+      </p>
     </div>
     <div class="span4">
       <h3>Use cases</h3>

docs/templates/pages/base-css.mustache

@@ -1461,7 +1461,10 @@
 <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>
-      <p>{{_i}}When using beside strings of text, as in buttons or nav links, be sure to leave a space after the <code>&lt;i&gt;</code> tag for proper spacing.{{/i}}</p>
+      <p>
+        <span class="label label-info">{{_i}}Heads up!{{/i}}</span>
+        {{_i}}When using beside strings of text, as in buttons or nav links, be sure to leave a space after the <code>&lt;i&gt;</code> tag for proper spacing.{{/i}}
+      </p>
     </div>
     <div class="span4">
       <h3>{{_i}}Use cases{{/i}}</h3>