[docs] [issue18767] csv documentation does not note default quote constant

Change by Irit Katriel : ---------- components: +Library (Lib) keywords: +easy versions: +Python 3.10, Python 3.8, Python 3.9 -Python 2.7, Python 3.3, Python 3.4 _______________________________________ Python tracker https://bugs.python.org/issue18767 _______________________________________