Added new JavaScript questions to README

[Jenesh18]

This pull request enhances the repository by adding new JavaScript interview questions and their solutions to the README file. Specifically, the following updates were made:

1. Added a detailed explanation of module scope in JavaScript, including examples and key features.
2. Followed the existing repository's structure and formatting for consistency.
3. Ensured the new content adds value for users preparing for JavaScript interviews

[Jenesh18]

Hi @avrame @ckpinguin @lliccien @avalla,
I hope you're doing well! I wanted to kindly follow up on this PR. Please let me know if there's anything I can improve or if additional details are needed. Looking forward to your feedback! 😊
Thank you for your time and effort in maintaining this project.

[ckpinguin]

Thank you, hope ur doin fine as well! Nothing big to add at the moment in my opinion, I will do more PR's for typos and small stuff as I'm progressing along my JS-repetition :-)
Maybe you could rename the project to something more generic like „JavaScript repetition & cheatsheet“. But that's just my opinion, because I'm not really interested in dev interviews, I just want to get fluent in JS/TS.