Run admin/update-copyright.

* tutorials/TUTORIAL, tutorials/TUTORIAL.cs, tutorials/TUTORIAL.eo:
* tutorials/TUTORIAL.es, tutorials/TUTORIAL.it, tutorials/TUTORIAL.ja:
* tutorials/TUTORIAL.ko, tutorials/TUTORIAL.nl, tutorials/TUTORIAL.pl:
* tutorials/TUTORIAL.pt_BR, tutorials/TUTORIAL.ro:
* tutorials/TUTORIAL.ru, tutorials/TUTORIAL.sk, tutorials/TUTORIAL.sv:
* tutorials/TUTORIAL.th:
Avoid using ` for natural-language quotes.  Instead, work around
the problem with "\" by using non-" quotation marks appropriate
for the natural language in question, e.g., «...» for Spanish.
For English “...” could be used, but use '...' instead so that
TUTORIAL continues to be encoded in ASCII.

Note that I had to change "\" to `\', because otherwise Emacs thought
that everything after that point was inside a string and so did not
indent anything.

So translators should check for anything similar in their translated
versions.

* doc/lispref/display.texi (Face Functions): Add an index.

* doc/lispref/variables.texi (Variable Aliases): Add an index.

* doc/lispref/functions.texi (Defining Functions): Add an index.

* doc/lispref/nonascii.texi (Coding System Basics): Add an index.

Fixes: debbugs:11689