Consider to clarify "use strict" concept

還沒有人認領這個 Issue。

Hello

About "use strict" in https://javascript.info/strict-mode is indicated:

> This was the case until 2009 when ECMAScript 5 (ES5) appeared. It added new features to the language and modified some of the existing ones. _To keep the old code working, most such modifications are off by default. You need to explicitly enable them with a special directive: "use strict"_

The italic part is not very clear (I read the spanish version too), it gives the idea that "use strict" enables the old mode code

Of course in https://javascript.info/javascript-specials#strict-mode is more clear with:

> _To fully enable all features of **modern JavaScript**, we should start scripts with "use strict"._

Thank you

從 javascript.info/strict-mode 和 javascript.info/javascript-specials#strict-mode 中關於嚴格模式的部分開始，並比較其中引用的說明。釐清斜體句子的含義，使其不會暗示 "use strict" 會啟用舊有行為；當說明符合更清楚的措辭並消除歧義時，即可視為完成。

由索引模型根據 Issue 內容生成。