fast-import doc: remove suggested 16-parent limit
Merges with an absurd number of parents are still a bad idea because
they do not render well in tools like gitk, but if they are present
in the repository being imported into git then there's no need to
avoid reproducing them faithfully.
In olden times, before v1.6.0-rc0~194 (2008-06-27), git commit-tree
and higher-level tools built on top of it were limited to writing 16
parents for a commit. Nowadays normal git operations are happy to
write more parents when asked, so the motivation for this note in the
fast-import documentation is gone and we can remove it.
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>