--filter and --hard-links man page improvements

[Wayne Davison]

On Mon, Feb 11, 2008 at 01:28:47AM -0500, Matt McCutchen wrote:
> you omitted the mention of
> --link-dest as a second potential source of unwanted hard links among
> destination files (the original focus of bug 3693).

Since the purpose of the --link-dest option is to create lots of extra
hard links to save space, I didn't think it needed to clutter up the
main point going on there.  It's true that the ancestral linking of the
files can keep files linked together that used to be linked together,
but only if a prior run had used -H, so I thought that the warning about
the -H option was sufficient.

..wayne..