Addition of new Category

[gaurav552]

Checklist:

• [x] I've read and understood Contributing Guidelines.
• [x] I've added the new resource at the end of its section.
• [x] This resource is out there for a while, and actively maintained.
• [x] This resource is popular enough and has at least a few hundred stars on GitHub.

---

This addition will create a new category in the existing list and adds a couple of packages under that category. Communications is an important category which i feel was missing from the list and I have included packages like WebRTC, Peer JS, and Socket IO. All of these packages helps user in client to client or Client to server communication which is very important when building real time communication system and I personally have used it to create multiplayer games. So i feel like these packages missing from this list was unjust.