jQuery.isFunction: Resolve ambiguity about what is being tested

Closes jquerygh-1079
Fixes jquerygh-1034

Author: gibson042

entries/jQuery.isFunction.xml

@@ -3,11 +3,11 @@
   <title>jQuery.isFunction()</title>
   <signature>
     <added>1.2</added>
-    <argument name="obj" type="PlainObject">
-      <desc>Object to test whether or not it is a function.</desc>
+    <argument name="value" type="Anything">
+      <desc>The value to be tested.</desc>
     </argument>
   </signature>
-  <desc>Determine if the argument passed is a JavaScript function object. </desc>
+  <desc>Determines if its argument is callable as a function.</desc>
   <longdesc>
     <p><strong>Note:</strong> As of jQuery 1.3, functions provided by the browser like <code>alert()</code> and DOM element methods like <code>getAttribute()</code> are not guaranteed to be detected as functions in browsers such as Internet Explorer.</p>
   </longdesc>