bug#53265: 26.3; Doc of `with-output-to-temp-buffer' etc.: Say there's no undo.

[Drew Adams]

Please document (in doc strings and (if mentioned there) in Elisp
manual) that `with-output-to-temp-buffer' and the like have no undo.

This applies to anything that sets `buffer-undo-list' to t and leaves it
with that value.  It applies to function `temp-buffer-window-setup' and
macros and functions that use it.

In GNU Emacs 26.3 (build 1, x86_64-w64-mingw32)
 of 2019-08-29
Repository revision: 96dd0196c28bc36779584e47fffcca433c9309cd
Windowing system distributor `Microsoft Corp.', version 10.0.19043
Configured using:
 `configure --without-dbus --host=x86_64-w64-mingw32
 --without-compress-install 'CFLAGS=-O2 -static -g3''