bug#24519: 25.1; doc string of `text-quoting-style'

[Drew Adams]

Please make clear that this variable (which should be a user
option, BTW) has *no effect* on Info (manuals, the most extensive
documentation).

The current doc string can easily give the impression that it affects
also Info.  Users do not necessarily distinguish the manuals from
what this doc string really means by "help".

  "Style to use for single quotes in help and messages."
                                     ^^^^

In GNU Emacs 25.1.1 (x86_64-w64-mingw32)
 of 2016-09-17
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --without-dbus --without-compress-install CFLAGS=-static'