[tldoc] tlguide for TeX Live 2016

[Karl Berry]

Hello TL documentation translators/volunteers - I've committed a first
cut at the documentation update for TeX Live 2016.  I don't expect there
to be many changes, hopefully none, aside from whatever you find in
updating the translations.

The goal is to have the final image ready by May 15, although the sooner
the translation updates can be done the better, of course.

There were the usual mechanical 2014 -> 2015 -> 2016 changes and the new
news section at the end.  I also decided to remove all uses of \acro
since it was never used consistently and was just a complication.

The "screenshots" of the text installer are updated to the current
pretest; the other screenshots aren't updated yet, but will be soon.

As usual, the previous year (2015)'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.

Also, please let me know if you will be unable to update your
translation so I can look for another volunteer.  To the best of my
knowledge, this is the current list:

  Carlos Enriquez Figueras (Spanish),
  Jjgod Jiang, Jinsong Zhao, Yue Wang, \& Helin Gai (Chinese),
  Nikola Le\v{c}i\'c (Serbian),
  Marco Pallante (Italian),
  Manuel P\'egouri\'e-Gonnard (French),
  Petr Sojka \& Jan Busa (Czech\slash Slovak),
  Boris Veytsman (Russian),
  Staszek Wawrykiewicz (Polish),
  Uwe Ziegenhagen (German).

Let me know about any updates.

On the tlmgr messages front: 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.  (Carlos: you should probably translate them for
Spanish, though; see readme-html.dir/readme.en.html and
readme-txt.dir/README.EN.)