Added MDN article How does the internet work MDN article

[emberavenge]

What roadmap does this PR target?

• [ ] Code Change
• [x] Frontend Roadmap
• [ ] Backend Roadmap
• [ ] DevOps Roadmap
• [ ] All Roadmaps
• [ ] Guides

Please acknowledge the items listed below

• [ ] I have discussed this contribution and got a go-ahead in an issue before opening this pull request.
• [x] This is not a duplicate issue. I have searched and there is no existing issue for this.
• [x] I understand that these roadmaps are highly opinionated. The purpose is to not to include everything out there in these roadmaps but to have everything that is most relevant today comparing to the other options listed.
• [x] I have read the contribution docs before opening this PR.

Enter the details about the contribution

Back a few months ago when I was learning frontend web development this article helped me understand with it's use of simple explanations and digestible easy to understand, and I think it's a good fit for it's excellent unpacking of such an important concept