bug#18027: 24.4.50; doc of `rectangle-mark-mode'

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

(emacs) `Rectangles' says this:

  The command `C-x <SPC>' (`rectangle-mark-mode') makes a "rectangular
  region".  It is a new feature introduced in GNU Emacs 24.4, and most
  commands now are still unaware of it, but kill and yank (*note
  Killing::) do work on the rectangle.

1. The manual should not be saying anything about something being new in
such-and-such a release.  It should always document the current release.
It can, if helpful, say something explicit about an older release, but
it has no business saying anything about "new" features.  New features
should be described in NEWS.

2. If some feature is limited, just say what the limitations are.  Do
not say anything about "currently" or "now".

3. This doc is not very helpful.  It does not say what a "rectangular
region" is or what it is for or what you can do with it or how.  It says
that this command makes one of these thingies, but it says nothing about
what it makes it from - in particular, it says nothing about the
relation of the region to "a rectangular region".  And it says nothing
about the appearance of the thing that it makes.  In short, it tells you
pretty much NOTHING about what this command is about.


In GNU Emacs 24.4.50.1 (i686-pc-mingw32)
 of 2014-06-28 on ODIEONE
Bzr revision: 117431 rgm@gnu.org-20140628015517-eku6hj8mpgcvfnso
Windowing system distributor `Microsoft Corp.', version 6.1.7601
Configured using:
 `configure --prefix=/c/Devel/emacs/snapshot/trunk
 --enable-checking=yes,glyphs 'CFLAGS=-O0 -g3'
 LDFLAGS=-Lc:/Devel/emacs/lib 'CPPFLAGS=-DGC_MCHECK=1
 -Ic:/Devel/emacs/include''