Documentation: Update the NFS remote examples to use the staging repo

Documentation: Update the NFS remote examples to use the staging repo

linux-nfs.org seems to have restructured their repository layout since
8391c60 (git-remote.txt: fix example url, 2007-11-02), and Bruce's
repo is now at git://git.linux-nfs.org/projects/bfields/linux.git.
Bruce also has a more richer internal branch structure (master,
everything, for-3.1, ...), so updating the existing example to use his
current repo may be confusing.

To simplify, I've replaced the NFS repo with Greg's staging repo.
I've also updated the output of the surrounding commands to match the
output of a current run through.

Signed-off-by: W. Trevor King <wking@tremily.us>
Signed-off-by: Junio C Hamano <gitster@pobox.com>