MTLLoader.MaterialCreator comment fix - edit original source, not derived jsm version

examples/js/loaders/MTLLoader.js

@@ -123,7 +123,7 @@ THREE.MTLLoader.prototype = Object.assign( Object.create( THREE.Loader.prototype
 } );
 
 /**
- * Create a new THREE-MTLLoader.MaterialCreator
+ * Create a new THREE.MTLLoader.MaterialCreator
  * @param baseUrl - Url relative to which textures are loaded
  * @param options - Set of options on how to construct the materials
  *                  side: Which side to apply the material