[tldoc] tl2021 manual translations

[Karl Berry]

    I don't remember if this has been discussed but anyway: I have
    been told that Mac OS X should now be called and written macOS.

Yes, it has been discussed, and yes, Apple marketing would like the
whole world to follow their cutesy changes. I resist. We'd just have to
change everything again in a few more years, because that's how
marketing people get paid.

MacOSX is still, as I understand it, technically correct (enough). I do
use "macOS" in a few places (not in the TL manual), but I'm not going to
go back and edit every document I ever wrote that mentions Macs.

If anyone wants to change it in the translations, I don't object. -k