Merge https://github.com/mrdoob/three.js into objects

docs/examples/en/exporters/GLTFExporter.html

@@ -33,6 +33,14 @@
 			<li>KHR_texture_transform</li>
 		</ul>
 
+		<p>
+			The following glTF 2.0 extension is supported by an external user plugin
+		</p>
+
+		<ul>
+			<li>[link:https://github.com/takahirox/three-gltf-plugins KHR_materials_variants]</li>
+		</ul>
+
 		<h2>Code Example</h2>
 
 		<code>

docs/examples/en/loaders/GLTFLoader.html

@@ -41,6 +41,14 @@
 			<li>MSFT_texture_dds</li>
 		</ul>
 
+		<p>
+			The following glTF 2.0 extension is supported by an external user plugin
+		</p>
+
+		<ul>
+			<li>[link:https://github.com/takahirox/three-gltf-plugins KHR_materials_variants]<sup>3</sup></li>
+		</ul>
+
 		<p><i>
 			<sup>1</sup>Requires [link:https://threejs.org/docs/#api/en/renderers/WebGLRenderer.physicallyCorrectLights physicallyCorrectLights] to be enabled.
 		</i></p>
@@ -54,6 +62,10 @@
 			#[link:https://github.com/mrdoob/three.js/issues/12788 12788].
 		</i></p>
 
+		<p><i>
+			<sup>3</sup>You can also manually process the extension after loading in your application. See [link:https://threejs.org/examples/#webgl_loader_gltf_variants Three.js glTF materials variants example].
+		</i></p>
+
 		<h2>Code Example</h2>
 
 		<code>

examples/js/loaders/GLTFLoader.js

@@ -2566,7 +2566,7 @@ THREE.GLTFLoader = ( function () {
 	 * Assigns final material to a Mesh, Line, or Points instance. The instance
 	 * already has a material (generated from the glTF material options alone)
 	 * but reuse of the same glTF material may require multiple threejs materials
-	 * to accomodate different primitive types, defines, etc. New materials will
+	 * to accommodate different primitive types, defines, etc. New materials will
 	 * be created if necessary, and reused from a cache.
 	 * @param  {THREE.Object3D} mesh Mesh, Line, or Points instance.
 	 */