bug#11175: 24.0.94; doc string of `customize-apropos'

[Drew Adams]

The doc string is not written well for users, that is, for interactive
use.  It should _first_ of all state clearly that:

* With no prefix arg, matching groups, faces, and options are
  customized.

* With a prefix arg, matching groups, faces, options, and non-option
  variables are customized.

Then it can go on to say what happens non-interactively wrt argument
TYPE.  Users should not have to read about TYPE to understand the
interactive use.

In GNU Emacs 24.0.94.1 (i386-mingw-nt5.1.2600)
 of 2012-03-19 on MARVIN
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.6) --no-opt --enable-checking --cflags
 -ID:/devel/emacs/libs/libXpm-3.5.8/include
 -ID:/devel/emacs/libs/libXpm-3.5.8/src
 -ID:/devel/emacs/libs/libpng-dev_1.4.3-1/include
 -ID:/devel/emacs/libs/zlib-dev_1.2.5-2/include
 -ID:/devel/emacs/libs/giflib-4.1.4-1/include
 -ID:/devel/emacs/libs/jpeg-6b-4/include
 -ID:/devel/emacs/libs/tiff-3.8.2-1/include
 -ID:/devel/emacs/libs/gnutls-3.0.9/include'