[tldistro] texlive2021 pretest images & rfp

[Karl Berry]

Hello TeX distro folks. We're currently in the pretest period for
TeX Live'21 -- news and other info at
https://tug.org/texlive/pretest.html.

The compiled sources are final-as-far-we-know, i.e., barring bad bugs.
If you have any patches you'd like to pass upstream, please let me know
asap.  The regular package updates will continue for a couple more
weeks.

I've built preliminary tarballs, etc., at
ftp://tug.org/texlive/Images/test/ as usual.  If anyone has a chance for
any testing or review, that would be great. --thanks, karl.