[tldoc] tl2024 guide translations

[Karl Berry]

I've done the basic updates for 2024 for the TL Guide (texlive-en.tex,
r69994). The screenshots still need to be updated (Siep ...?), but I
think the rest is pretty stable.

The volunteer doing the Polish translation has stepped down, so if
anyone is interested in taking that up, let me know. The zh_CN and
zh_TW translations also need volunteers to resume.

I changed the English to typeset at [12pt], just to make it easier to
read on screens. This meant fixing a dozen or so over/underfull
boxes. There is no particular need to reflect those minor wording tweaks
in the translations. As you wish ... I did update some links in passing
(https, etc.), which you'll probably want to take.

The current sources are committed to svn. If you don't have an svn
checkout, you can download texlive-en.tex and tex-live.sty from
  http://tug.org/svn/texlive/trunk/Master/texmf-dist/doc/texlive/texlive-en/
Let me know if any difficulties getting the new stuff.

Also as usual, for your (w)diff pleasure, the previous year (2023)'s
files are in the archive/ subdir of
Master/texmf-dist/doc/texlive/texlive-en/ in the TL tree, aka
https://tug.org/svn/texlive/trunk/Master/texmf-dist/doc/texlive/texlive-en/archive/

I don't plan to make any changes to the top-level README this year, 
and I don't think much is going to happen with the .po files, either,
apart from updating the year.

Let me know if any questions or problems, as usual. --thanks, karl.