package auth
...
auth = route.Group("/auth"){
    auth.GET(...
    auth.POST(...
}
...

package users
...
user = route.Group("/user"){
    user.GET(...
    user.POST(...
}
...

package main
import (
     "auth"
     "users"
)
...
router = gin.Default()
router.Register(auth.auth, users.user)
router.Run()
...

package auth
import "...gin"
func Routes(route *gin.Engine)
auth := route.Group("/auth"){
    auth.GET(...
    auth.POST(...
}
...

package users
import "...gin"
func Routes(route *gin.Engine)
user := route.Group("/user"){
    user.GET(...
    user.POST(...
}
...

package main
import (
     "github.com/username/package/sub/auth"
     "github.com/username/package/sub/users"
     "github.com/gin-gonic/gin"
)
...
router := gin.Default()
auth.Routes(router) //Added all auth routes
user.Routes(router) //Added all user routes
router.Run()
...