[3.12] pythongh-116633: Add a note about buggy behavior of csv.QUOTE_NOTNULL and csv.QUOTE_STRINGS (pythonGH-117235)

* Add a note about bug

* Properly link constants

Author: Prometheus3375

Doc/library/csv.rst

@@ -365,6 +365,12 @@ The :mod:`csv` module defines the following constants:
 
    .. versionadded:: 3.12
 
+.. note::
+
+   Due to a bug, constants :data:`QUOTE_NOTNULL` and :data:`QUOTE_STRINGS`
+   do not affect behaviour of :class:`reader` objects.
+   This bug is fixed in Python 3.13.
+
 The :mod:`csv` module defines the following exception: