bug#53261: 26.3; Doc of `load-history' should say what the alist order is.

[Drew Adams]

The doc of `load-history' describes the alist entries in detail.  But it
should also say that the list entries are in reverse chronological order
of loading, i.e., earliest loaded libraries at the end, most recently
loaded entries at the beginning.

This may be obvious if you assume the simplest construction of the
alist.  It's nevertheless important information to mention in the doc.

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''