Fix: markdown typo - extra`

**Confusion**
Please Check this line.
We'll come back to the important differences between these two operations in the Chapter 5 when we explore `[[Prototype]]`s in detail.

Is **`[[Prototype]]`s** in above line, same as **`myObject`'s**
if yes then it should be **`[[Prototype]]`'s** otherwise it should be **`[[Prototype]]`** withous 's'

Please check and confirm. I will fix.