Replace "remote tracking" with "remote-tracking"

Replace "remote tracking" with "remote-tracking"

"remote-tracking" branch makes it explicit that the branch is "tracking a
remote", as opposed to "remote, and tracking something".

See discussion in e.g.
http://mid.gmane.org/8835ADF9-45E5-4A26-9F7F-A72ECC065BB2@gmail.com
for more details.

This patch is a straightforward application of

  perl -pi -e 's/remote tracking branch/remote-tracking branch/'

except in the RelNotes directory.

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>