Add Jonathan Tan to git.git-authors Jonathan has consented via email to have his contributions to git reused in libgit2
diff --git a/git.git-authors b/git.git-authors
index 6a85224..3bc009f 100644
--- a/git.git-authors
+++ b/git.git-authors
@@ -53,6 +53,7 @@ ok Jeff King <peff@peff.net>
ok Johannes Schindelin <Johannes.Schindelin@gmx.de>
ok Johannes Sixt <j6t@kdbg.org>
ask Jonathan Nieder <jrnieder@gmail.com>
+ok Jonathan Tan <jonathantanmy@google.com>
ok Junio C Hamano <gitster@pobox.com>
ok Kristian Høgsberg <krh@redhat.com>
ok Linus Torvalds <torvalds@linux-foundation.org>