doc: fast-import: contextualize the hardware cost
6e411d20440 (Initial draft of fast-import documentation., 2007-02-05)
pointed out how much time a fast-import took on some hardware with a
specific cost. Let’s further point out that this experiment was done
in 2007. So modern hardware should have no issues with such a repo.
Also move the parenthetical to the end now that it contains four words.
Signed-off-by: Kristoffer Haugsbakk <code@khaugsbakk.name>
Signed-off-by: Junio C Hamano <gitster@pobox.com>