bpo-33297: Mention Pillow to work with more image formats. (GH-6505)


Also update PIL doc references to Pillow.
(cherry picked from commit b81ca28b378c8b29204a37f8bd433a3379f53f7d)

Co-authored-by: Andrés Delfino <34587441+andresdelfino@users.noreply.github.com>
3 files changed