bug#12172: 24.1.50; doc string of `special-display-popup-frame'

[Drew Adams]

(This is minor.)
 
The first line of a function's doc string should give and overall idea
of what it does.
 
The first line of this doc string says nothing about what the function
does that makes it different from just displaying a buffer normally.
IOW, it indicates nothing about "special display" or "frame".
 
It should at least make the point that BUFFER is popped up in a frame.
That is sufficiently vague to cover all of the cases, I think, including
cases where BUFFER is already displayed somewhere: a frame showing it is
simply raised in that case.
 
Here is a suggested first line for the doc string:
 
 Pop up a frame displaying BUFFER.  Return its window.
 
Or you could move that second sentence later.

In GNU Emacs 24.1.50.1 (i386-mingw-nt5.1.2600)
 of 2012-08-08 on DANI-PC
Bzr revision: 109511 michael.albinus@gmx.de-20120808134045-t26l1voivvzfypey
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.7) --no-opt --enable-checking --cflags
 -I../../libs/libxpm-3.5.8/include -I../../libs/libxpm-3.5.8/src
 -I../../libs/libpng-1.4.10 -I../../libs/zlib-1.2.6
 -I../../libs/giflib-4.1.4-1/include -I../../libs/jpeg-6b-4/include
 -I../../libs/tiff-3.8.2-1/include
 -I../../libs/libxml2-2.7.8-w32-bin/include/libxml2
 -I../../libs/gnutls-3.0.16/include
 -I../../libs/libiconv-1.14-2-mingw32-dev/include'