Effect: Fix typo

Closes jquerygh-1778

Author: lukeb

ui/effect.js

@@ -1359,7 +1359,7 @@ $.fn.extend( {
 var el = $( this ),
 normalizedMode = $.effects.mode( el, mode ) || defaultMode;
 
-// Sentinel for duck-punching the :animated psuedo-selector
+// Sentinel for duck-punching the :animated pseudo-selector
 el.data( dataSpaceAnimated, true );
 
 // Save effect mode for later use,