[3.13] gh-140826: Update winreg's docstring (GH-141050) (GH-141200) (GH-141209)

(cherry picked from commit bea0d3d12bcd122d8498b92cdd6c724822fd6505)
(cherry picked from commit b3377c3b417cb3b3162623eeba740cb366df35d5)

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: AN Long <aisk@users.noreply.github.com>