Update DirectionalLight.html

docs/api/lights/DirectionalLight.html

@@ -30,7 +30,7 @@ scene.add( directionalLight );</code>
 
 		<h3>[name]([page:todo hex], [page:todo intensity])</h3>
 		<div>
-		hex -- todo <br />
+		hex -- Numeric value of the RGB component of the color. <br />
 		intensity -- todo
 		</div>
 		<div>