[docs] [issue13828] Further improve casefold documentation

Cheryl Sabella <cheryl.sabella@gmail.com> added the comment: Assigning to @Mariatta for the sprints. ---------- assignee: docs@python -> Mariatta nosy: +Mariatta, cheryl.sabella stage: -> needs patch versions: +Python 3.7, Python 3.8 -Python 3.3 _______________________________________ Python tracker <report@bugs.python.org> <https://bugs.python.org/issue13828> _______________________________________