[tldoc] time for 2018 TL manual translations, please

[Karl Berry]

Hello TL documentation translators/volunteers - sorry it's so late, but
the main documentation update for TeX Live 2018 is committed now.
I don't expect there to be many more changes to the original (hopefully
none), aside from anything you find in updating the translations.

The goal is to have the final TL release ready by April 16, although the
sooner the translations can be updated the better, of course.

There were the usual mechanical 2015 -> 2016 -> 2017 changes and new
news section at the end, a number of url updates, a few other tweaks.
Nothing major.

As usual, for your (w)diff pleasure, the previous year (2017)'s files
are in the archive/ subdir of Master/texmf-dist/doc/texlive/texlive-en/
in the TL tree, aka
http://tug.org/svn/texlive/trunk/Master/texmf-dist/doc/texlive/texlive-en/archive/

Let me know if any questions or problems, of course.

As for tlmgr messages: I imagine there have been some string changes
that need updated translations, but haven't looked into specifics.

Happy translating,
Karl

P.S. I hope it will not be necessary to update the top-level README
files this year; I know of no reason to do.