bug#67577: 29.1; Comments in kill-region seem to explain unless wrong

[Eli Zaretskii]

> From: Xiyue Deng <manphiz@gmail.com>
> Date: Fri, 01 Dec 2023 21:36:11 -0800
> 
> 
> It says "'unless' is an 'if' without the then-part", which I think it
> meant to say "'unless' is the inverse of 'if' ...", as I think "an 'if'
> without the then-part" is supposed to be 'when'.  Let me know if my
> understanding is wrong.  If not, please find the patch in my next post.

We already fixed that part.  The text now says:

     The ‘kill-region’ function definition also has an ‘unless’ macro; it
  is the opposite of ‘when’.  The ‘unless’ macro is like an ‘if’ except
  that it has no then-clause, and it supplies an implicit ‘nil’ for that.

So I don't think this needs to be fixed anymore.