Docs: Change 'req' to 'res' for fetch handler

threejs/lessons/ja/threejs-optimize-lots-of-objects.md

@@ -46,8 +46,8 @@ three.jsには最適化する方法は多々あります。1つの方法は*ジ
 
 ```js
 async function loadFile(url) {
-  const req = await fetch(url);
-  return req.text();
+  const res = await fetch(url);
+  return res.text();
 }
 ```
 

threejs/lessons/kr/threejs-optimize-lots-of-objects.md

@@ -48,8 +48,8 @@ Three.js에서 요소를 최적화하는 방법은 아주 다양합니다. 가
 
 ```js
 async function loadFile(url) {
-  const req = await fetch(url);
-  return req.text();
+  const res = await fetch(url);
+  return res.text();
 }
 ```
 

threejs/lessons/ru/threejs-optimize-lots-of-objects.md

@@ -52,8 +52,8 @@ TOC: Оптимизация большого количества объекто
 
 ```js
 async function loadFile(url) {
-  const req = await fetch(url);
-  return req.text();
+  const res = await fetch(url);
+  return res.text();
 }
 ```
 

threejs/lessons/threejs-optimize-lots-of-objects.md

@@ -57,8 +57,8 @@ First some code to load the text file
 
 ```js
 async function loadFile(url) {
-  const req = await fetch(url);
-  return req.text();
+  const res = await fetch(url);
+  return res.text();
 }
 ```