refactor: repository pattern: rename Save() to Create()

internal/postgres/training_repository.go

@@ -14,7 +14,7 @@ func NewTrainingRepository(db *sql.DB) *TrainingRepository {
 	return &TrainingRepository{db: db}
 }
 
-func (r *TrainingRepository) Save(t *training.Training) error {
+func (r *TrainingRepository) Create(t *training.Training) error {
 	_, err := r.db.Exec("INSERT INTO training (id, name, days, description, price) VALUES ($1, $2, $3)", t.ID, t.Name, t.Days, t.Description, t.Price)
 	return err
 }