Fixed a typo.

docs/api/objects/Sprite.html

@@ -11,7 +11,7 @@
 
 		<h1>[name]</h1>
 
-		<div class="desc">A sprite is an plane in an 3d scene which faces always towards the camera. </div>
+		<div class="desc">A sprite is a plane in an 3d scene which faces always towards the camera. </div>
 
                 <h2>Example</h2>