[Rd] one suggestion for R-admin

[Liaw, Andy]

Just one minor point about building bitmap.dll on Windows in
doc/manual/R-admin.texi:

In lines 601-605:

@item
You need @code{libpng} and @code{jpeg} sources (available, e.g., from
@url{http://www.libpng.org}, @url{ftp://ftp.uu.net/graphics/}[png,jpeg].
You will need files @file{libpng-1.2.8.tar.gz} and
@file{jpegsrc.v6b.tar.gz} or later.

and lines 699-707:

The file @file{@var{R_HOME}/bin/Rbitmap.dll} is not built automatically:
instructions on how to build it are in the file @file{bitmap/INSTALL}.

If everything is set up in directory @file{bitmap},
@example
make bitmapdll
@end example
@noindent
will work from this directory.

Why not just add the instruction in src/gnuwin32/bitmap/INSTALL into these
places?  It seems like unnecessary work to go find the few lines of
instruction in a different file...  (Especially in the first part quoted
above:  It tells what to get the files, but not where to put them.)

Best,
Andy