[BACKEND] Add Session Management

[Asac2142]

Roadmap URL

https://roadmap.sh/backend

Suggestions

Besides knowing what is authentication/authorization, the types of it, how to handle it in your web service, etc... I think it should also add the topic for Session Management, what is SM, how to implement it, types of SM?

I am someone who is learning backend, and I am not sure if SM is something relevant. I think it is an important topic to be learned.