Docs: fix untranslated parts (#23445)

docs/manual/zh/introduction/Loading-3D-models.html

@@ -69,8 +69,7 @@
 	<h2>加载</h2>
 
 	<p>
-		Only a few loaders (e.g. [page:ObjectLoader]) are included by default with
-		three.js — others should be added to your app individually.
+		在three.js中只会内置一部分加载器（例如：[page:ObjectLoader]） —— 其它的需要在你的应用中单独引入。
 	</p>
 
 	<code>