Documentation: Add node on physically correct lights in glTF.

docs/examples/loaders/GLTFLoader.html

@@ -31,13 +31,16 @@
 			<li>KHR_draco_mesh_compression</li>
 			<li>KHR_materials_pbrSpecularGlossiness</li>
 			<li>KHR_materials_unlit</li>
-			<li>KHR_lights_punctual</li>
-			<li>KHR_texture_transform<sup>*</sup></li>
+			<li>KHR_lights_punctual<sup>1</sup></li>
+			<li>KHR_texture_transform<sup>2</sup></li>
 			<li>MSFT_texture_dds</li>
 		</ul>
 
 		<p><i>
-			<sup>*</sup>UV transforms are supported, with several key limitations. Transforms applied to
+			<sup>1</sup>Requires [link:https://threejs.org/docs/#api/en/renderers/WebGLRenderer.physicallyCorrectLights renderer.physicallyCorrectLights=true].
+		</i></p>
+		<p><i>
+			<sup>2</sup>UV transforms are supported, with several key limitations. Transforms applied to
 			a texture using the first UV slot (all textures except aoMap and lightMap) must share the same
 			transform, or no transfor at all. The aoMap and lightMap textures cannot be transformed. No
 			more than one transform may be used per material. Each use of a texture with a unique