[Typo]- In chapter Arrays in the section of loops we have to change `number` to `index`

In chapter Arrays 's section Loops there in sentence The for..of doesn’t give access to the **number** of the current element, just its value, but in most cases that’s enough. And it’s shorter.
Instead of number we have to use index.
Because using number is not really telling us we're talking about index or number (which can be value)

[X] I would love to work on this issue.

開啟連結教學頁面中的 Arrays 章節及其 Loops 部分，然後找到關於 for..of 和目前元素的句子。將不準確的術語「number」改為「index」，並確認該句清楚地描述了目前元素的索引；未提及測試。