bug#9711: 24.0.50; doc string of defcustom

[Drew Adams]

There is a horrible confusion because of the different uses of `VALUE'
in two different contexts: in the ARG list and in this: 
 
"The remaining arguments should have the form
 
   [KEYWORD VALUE]..."
 
After that, the keywords are described, with VALUE presumably being
different for each one.  That's OK, but we should not be using the same
name, "VALUE" for the argument in the arglist.
 
In GNU Emacs 24.0.50.1 (i386-mingw-nt5.1.2600)
 of 2011-09-19 on 3249CTO
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.5) --no-opt'