code: func Delete(c *gin.Context) {
  	db := c.MustGet("db").(*mgo.Database)
  	query := bson.M{"_id": bson.ObjectIdHex(c.Param("_id"))}
  	err := db.C(models.CollectionArticle).Remove(query)
  	if err != nil {
  		c.Error(err)
  	}
  	c.Redirect(http.StatusMovedPermanently, "/articles")
  }
docs: // Delete an article