Add callout to docs: LESS compiler support

docs/getting-started.html

@@ -48,6 +48,11 @@ lead: "An overview of Bootstrap, how to download and use, basic templates and ex
 <!-- Latest compiled and minified JavaScript -->
 <script src="//netdna.bootstrapcdn.com/bootstrap/3.0.0/js/bootstrap.min.js"></script>
 {% endhighlight %}
+
+    <div class="bs-callout">
+      <h4>LESS compilation</h4>
+      <p>If you download the original source files, you need to compile Bootstrap's LESS files into usable CSS. While there are various LESS compilers available, Bootstrap only supports the latest stable version of <a href="http://lesscss.org/">less.js</a>.</p>
+    </div>
   </div>
 
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