bug#10722: 24.0.93; doc of file-name predicates

[Drew Adams]

See (elisp) `Testing Accessibility', and the doc strings of the
predicates described in that node.
 
I see nothing that tells you how the argument FILENAME is used to check
existing files.  In particular, there is nothing that says whether
FILENAME must be absolute or relative or can be either, and nothing, in
the relative case, that says what directory is assumed.
 
The doc should state that FILENAME can be absolute or relative, and if
relative then directory `default-directory' is assumed.

In GNU Emacs 24.0.93.1 (i386-mingw-nt5.1.2600)
 of 2012-01-29 on MARVIN
Windowing system distributor `Microsoft Corp.', version 5.1.2600
Configured using:
 `configure --with-gcc (4.6) --no-opt --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 --ldflags
 -LD:/devel/emacs/libs/gnutls-3.0.9/lib'