fix replace to replace all

[ahmedengu]

Greetings,

Replace was replacing only the first occurrence, but it was meant to replace all, as per the example explained in the v5 course.

It's a really common mistake; we forget about the quirky replace all the time! So I updated the code and added comments to help others avoid this mistake https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace

Best Regards, Ahmed