Update DepthTexture.html

docs/api/en/textures/DepthTexture.html

@@ -121,7 +121,8 @@
 
 		<h3>[property:number compareFunction]</h3>
 		<p>
-		This is used to define the comparison function used when comparing texels in the depth texture to the value in the depth buffer.<br /><br/>
+		This is used to define the comparison function used when comparing texels in the depth texture to the value in the depth buffer. 
+		Default is *null* which means comparison is disabled.<br /><br/>
 
 		See the [page:Textures texture constants] page for details of other functions.
 		</p>