Add the warning about deep=false to the short description as well

Author: Matthew Flaschen

entries/jQuery.extend.xml

@@ -16,7 +16,7 @@
   <signature>
     <added>1.1.4</added>
     <argument name="deep" optional="true" type="Boolean">
-      <desc>If true, the merge becomes recursive (aka. deep copy).</desc>
+      <desc>If true, the merge becomes recursive (aka. deep copy).  Passing <code>false</code> for this argument is not supported.</desc>
     </argument>
     <argument name="target" type="Object">
       <desc>The object to extend. It will receive the new properties.</desc>