Make Objects Plural Again

[jakubmanczak]

Words contained inside endpoints are typically plural, and I'd extend that to modules as well. e.g.:

• we have GET ::/user which shows all users. Silly! And for GET ::/user/{id}, the point is that out of all users, we get a specific one -> GET ::/users/{id}.
• we have crate::users but crate::tournament

[Mateusz-Dobrzynski]

I agree. GET /user showing all users is obviously silly. We can change all endpoints to plural for consistency.