bug#13056: 24.2.50; sort-subr doc-string and manual

[Chong Yidong]

martin rudalics <rudalics@gmx.at> writes:

> The doc-string of `sort-subr' says that
>
>   PREDICATE is the function to use to compare keys.  If keys are numbers,
>   it defaults to `<', otherwise it defaults to `string<'.
>
> and the Elisp manual says something similar.  This is slightly
> misleading ever since this change
>
> 1993-02-07  Richard Stallman  (rms@mole.gnu.ai.mit.edu)
>
>       * sort.el (sort-build-lists): Record the key as pair of positions;
>       don't copy string from buffer.
>       (sort-subr): Use compare-buffer-substrings.

Fixed, thanks.