bug#21315: 25.0.50; doc of `kill-ring-save', `copy-region-as-kill' - bad

[Drew Adams <drew.adams@oracle.com>]

In Emacs 24.4 you changed not only the signature of these commands but
also their interactive behavior, by adding optional arg REGION and
giving users control over it with the prefix arg.

Unfortunately, the doc for this new behavior is horribly inadequate.

1. The Emacs manual says nothing about the new behavior.  It should
   cover it.

2. The doc strings are awful in this regard.  They say only "The
   optional argument REGION if non-nil, indicates that we're not just
   copying some text between BEG and END, but we're copying the region."

   That's worse than saying nothing - a complete cop-out.  If the doc is
   going to say something like "we're copying the region" and if that
   phrase is expected to mean anything then the doc needs to say what it
   means by that.  Describe the user-observable behavior difference
   between using a prefix arg and not using it.

   Currently, the use of a prefix arg is not even mentioned.  As bad as
   the description of parameter REGION is, it is not even connected with
   the use of a prefix arg.

3. The command is not documented at all in the Elisp manual.  It need
   not be, but the current state is that a user has no real information
   about this at all, and that is not good.

4. I find nothing in NEW for Emacs 24.4 (when this was released) about
   this.  User-observable behavior changes like this should be
   documented there.

<rant>Developers should not be allowed to commit program changes like
this without updating the doc appropriately.  Yes, leader resources are
scarce, and people are overworked.  But it's too bad, as it fosters bad
habits, unless the person who committed the code change happens to be
the one who fixes this doc bug, and can thus learn from the
mistake.</rant>

In GNU Emacs 25.0.50.1 (i686-pc-mingw32)
 of 2015-07-31 on LEG570
Bzr revision: 8d332aeccab2208e6c6bd434738565e6abf12043
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --host=i686-pc-mingw32 --enable-checking=yes,glyphs'