Consider renaming `Footer` to `Footnote`

[Igor Velikorossov]

During an internal usability study for the TaskDialog API, some users were confused by Footer

If there is a Footer, why there's no Header?
Footer without header??

https://docs.microsoft.com/en-us/windows/win32/uxguide/win-dialog-box uses "Footnote" name. Perhaps it is worth renaming the control to use that name.

[Konstantin Preißer]

I renamed it to Footnote/TaskDialogFootnote.

[Igor Velikorossov]

Awesome, thank you