Update jquery.parallax-1.1.3.js

Rename parameter and change position.

New JS (load before body element) for auto-load all parallax elements:

$(document).ready(function(){
	$('.ab-parallax').each(function() {
		xpos  = $(this).attr('parallax-xpos');
		ypos  = $(this).attr('parallax-ypos');
		speed = $(this).attr('parallax-speed');
		$(this).parallax(xpos, ypos, speed);
	});
})

And new usage in html :

<div id="intro" **class="ab-parallax" parallax-xpos="50%" parallax-ypos="100" parallax-speed="0.8"**>
	<!-- content here -->
</div>

Please update documentation if you approve my work :)