Implementation of route to get, add and filter. Addition of API docs. Other small fixes

[formidablae]

• Added API docs and collections from Postman (Closes Add postman collections #20 , Add API OpenAPI docs #19 )
• Corrected directory paths for migrations and seeders
• Fixed schema of OpenAPI docs for Users, Restaurants and Reservations to be arrays of their objects
• Added Reservation model (Closes Add Reservation model #21 )
• Added reservation service (Closes Add reservation service #22
• Renamed database and users services
• Updated User and Restaurant models
• Fixed UserController to return a message when there are no users found (Closes Add a return a message in UserController when there are no users found #23 )
• Added a restaurants service (Closes Add a restaurants service #24 )
• Added routes for restaurants and reservations (Closes Add routes for restaurants and reservations #25 )
• Added RestaurantController and ReservationController to get and add restaurants and reservations. Reservations can be filtered by a date range (Closes Add RestaurantController and ReservationController #26 )
• Added routes to get and add restaurants and reservations