bug#34263: 26.1; documentation for kmacro-insert-counter C-u is wrong

[Eli Zaretskii]

> Date: Fri, 01 Feb 2019 12:00:09 +0200
> From: Eli Zaretskii <eliz@gnu.org>
> Cc: 34263@debbugs.gnu.org
> 
> How do you suggest to define "previous" to avoid the confusion?  That
> was the reason for bug#31243.  We must add to the documentation the
> definition of "previous" that would be clear and unequivocal.

Never mind, I think I found a good way of explaining what is the
"previous" counter value, and fixed the docs accordingly.  Take a look
at the emacs-26 branch.

Thanks.