feat: updated docs and added description to files

Backend/models/booking.go

@@ -1,5 +1,11 @@
 package models
 
+// this file has all functions and types to handle bookings
+// the bookings itself are later combined to a workday to save on
+// db requests and computation
+//
+// the booking data is based on the entries in the "anwesenheit" database table
+
 import (
 	"arbeitszeitmessung/helper"
 	"arbeitszeitmessung/helper/logs"
@@ -39,7 +45,7 @@ type IDatabase interface {
 
 var DB IDatabase
 
-func (b *Booking) New(cardUid string, gereatId int16, checkInOut int16, typeId int8) Booking {
+func (b *Booking) NewBooking(cardUid string, gereatId int16, checkInOut int16, typeId int8) Booking {
 	bookingType, err := GetBookingTypeById(typeId)
 	if err != nil {
 		log.Printf("Cannot get booking type %d, from database!", typeId)