Note required callback arg in jQuery.post, close jquerygh-124.

Author: dmethvin

entries/jQuery.post.xml

@@ -12,7 +12,7 @@
       <desc>A plain object or string that is sent to the server with the request.</desc>
     </argument>
     <argument name="success(data, textStatus, jqXHR)" optional="true" type="Function">
-      <desc>A callback function that is executed if the request succeeds.</desc>
+      <desc>A callback function that is executed if the request succeeds. Required if <code>dataType</code> is provided, but can be <code>null</code> in that case.</desc>
     </argument>
     <argument name="dataType" optional="true" type="String">
       <desc>The type of data expected from the server. Default: Intelligent Guess (xml, json, script, text, html).</desc>