Reworded the notice as a caution

Author: javiereguiluz

components/dom_crawler.rst

@@ -231,7 +231,12 @@ and :phpclass:`DOMNode` objects:
         $html = $crawler->html();
 
     The ``html`` method is new in Symfony 2.3.
-    In PHP < 5.3.6 it might return html entities which are not properly decoded.
+
+    .. caution::
+
+        Due to an issue in PHP, the ``html()`` method returns wrongly decoded HTML
+        entities in PHP versions lower than 5.3.6 (for example, it returns ``•``
+        instead of ``&bull;``).
 
 Links
 ~~~~~